diff --git a/internal/cli/openvpnconfig.go b/internal/cli/openvpnconfig.go
index 1ccdeaf5..9a489125 100644
--- a/internal/cli/openvpnconfig.go
+++ b/internal/cli/openvpnconfig.go
@@ -34,7 +34,11 @@ func (c *CLI) OpenvpnConfig(logger logging.Logger, env params.Interface) error {
 	if err != nil {
 		return err
 	}
-	lines := providerConf.BuildConf(connection, allSettings.VPN.OpenVPN)
+	lines, err := providerConf.BuildConf(connection, allSettings.VPN.OpenVPN)
+	if err != nil {
+		return err
+	}
+
 	fmt.Println(strings.Join(lines, "\n"))
 	return nil
 }
diff --git a/internal/configuration/custom.go b/internal/configuration/custom.go
new file mode 100644
index 00000000..544a18e0
--- /dev/null
+++ b/internal/configuration/custom.go
@@ -0,0 +1,53 @@
+package configuration
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/golibs/params"
+)
+
+var (
+	errCustomNotSupported    = errors.New("custom provider is not supported")
+	errCustomExtractFromFile = errors.New("cannot extract configuration from file")
+)
+
+func (settings *Provider) readCustom(r reader, vpnType string) (err error) {
+	settings.Name = constants.Custom
+
+	if vpnType != constants.OpenVPN {
+		return fmt.Errorf("%w: for VPN type %s", errCustomNotSupported, vpnType)
+	}
+
+	return settings.readCustomOpenVPN(r)
+}
+
+func (settings *Provider) readCustomOpenVPN(r reader) (err error) {
+	configFile, err := r.env.Get("OPENVPN_CUSTOM_CONFIG", params.CaseSensitiveValue(), params.Compulsory())
+	if err != nil {
+		return fmt.Errorf("environment variable OPENVPN_CUSTOM_CONFIG: %w", err)
+	}
+	settings.ServerSelection.OpenVPN.ConfFile = configFile
+
+	// For display and consistency purposes only,
+	// these values are not actually used since the file is re-read
+	// before each OpenVPN start.
+	_, connection, err := r.ovpnExt.Data(configFile)
+	if err != nil {
+		return fmt.Errorf("%w: %s", errCustomExtractFromFile, err)
+	}
+	settings.ServerSelection.OpenVPN.TCP = connection.Protocol == constants.TCP
+
+	return nil
+}
+
+func (settings *OpenVPN) readCustom(r reader) (err error) {
+	settings.ConfFile, err = r.env.Path("OPENVPN_CUSTOM_CONFIG",
+		params.Compulsory(), params.CaseSensitiveValue())
+	if err != nil {
+		return fmt.Errorf("environment variable OPENVPN_CUSTOM_CONFIG: %w", err)
+	}
+
+	return nil
+}
diff --git a/internal/configuration/openvpn.go b/internal/configuration/openvpn.go
index cdcfafcd..4a7c4668 100644
--- a/internal/configuration/openvpn.go
+++ b/internal/configuration/openvpn.go
@@ -21,7 +21,7 @@ type OpenVPN struct {
 	Root      bool     `json:"run_as_root"`
 	Cipher    string   `json:"cipher"`
 	Auth      string   `json:"auth"`
-	Config    string   `json:"custom_config"`
+	ConfFile  string   `json:"conf_file"`
 	Version   string   `json:"version"`
 	ClientCrt string   `json:"-"`                 // Cyberghost
 	ClientKey string   `json:"-"`                 // Cyberghost, VPNUnlimited
@@ -59,8 +59,8 @@ func (settings *OpenVPN) lines() (lines []string) {
 		lines = append(lines, indent+lastIndent+"Custom auth algorithm: "+settings.Auth)
 	}
 
-	if len(settings.Config) > 0 {
-		lines = append(lines, indent+lastIndent+"Custom configuration: "+settings.Config)
+	if settings.ConfFile != "" {
+		lines = append(lines, indent+lastIndent+"Configuration file: "+settings.ConfFile)
 	}
 
 	if settings.ClientKey != "" {
@@ -83,13 +83,14 @@ func (settings *OpenVPN) lines() (lines []string) {
 }
 
 func (settings *OpenVPN) read(r reader, serviceProvider string) (err error) {
-	settings.Config, err = r.env.Get("OPENVPN_CUSTOM_CONFIG", params.CaseSensitiveValue())
-	if err != nil {
-		return fmt.Errorf("environment variable OPENVPN_CUSTOM_CONFIG: %w", err)
+	credentialsRequired := false
+	switch serviceProvider {
+	case constants.Custom:
+	case constants.VPNUnlimited:
+	default:
+		credentialsRequired = true
 	}
 
-	credentialsRequired := settings.Config == "" && serviceProvider != constants.VPNUnlimited
-
 	settings.User, err = r.getFromEnvOrSecretFile("OPENVPN_USER", credentialsRequired, []string{"USER"})
 	if err != nil {
 		return fmt.Errorf("environment variable OPENVPN_USER: %w", err)
@@ -159,6 +160,8 @@ func (settings *OpenVPN) read(r reader, serviceProvider string) (err error) {
 	}
 
 	switch serviceProvider {
+	case constants.Custom:
+		err = settings.readCustom(r) // read OPENVPN_CUSTOM_CONFIG
 	case constants.Cyberghost:
 		err = settings.readCyberghost(r)
 	case constants.PrivateInternetAccess:
diff --git a/internal/configuration/openvpn_test.go b/internal/configuration/openvpn_test.go
index 2c58f488..cdbd775f 100644
--- a/internal/configuration/openvpn_test.go
+++ b/internal/configuration/openvpn_test.go
@@ -25,7 +25,7 @@ func Test_OpenVPN_JSON(t *testing.T) {
   "run_as_root": true,
   "cipher": "",
   "auth": "",
-  "custom_config": "",
+  "conf_file": "",
   "version": "",
   "encryption_preset": "",
   "ipv6": false,
diff --git a/internal/configuration/provider.go b/internal/configuration/provider.go
index d6a30f13..6df395fe 100644
--- a/internal/configuration/provider.go
+++ b/internal/configuration/provider.go
@@ -49,6 +49,8 @@ func (settings *Provider) read(r reader, vpnType string) error {
 	}
 
 	switch settings.Name {
+	case constants.Custom:
+		err = settings.readCustom(r, vpnType)
 	case constants.Cyberghost:
 		err = settings.readCyberghost(r)
 	case constants.Fastestvpn:
@@ -99,6 +101,7 @@ func (settings *Provider) readVPNServiceProvider(r reader, vpnType string) (err
 	switch vpnType {
 	case constants.OpenVPN:
 		allowedVPNServiceProviders = []string{
+			constants.Custom,
 			"cyberghost", "fastestvpn", "hidemyass", "ipvanish", "ivpn", "mullvad", "nordvpn",
 			"privado", "pia", "private internet access", "privatevpn", "protonvpn",
 			"purevpn", "surfshark", "torguard", constants.VPNUnlimited, "vyprvpn", "windscribe"}
@@ -115,6 +118,11 @@ func (settings *Provider) readVPNServiceProvider(r reader, vpnType string) (err
 	if vpnsp == "pia" { // retro compatibility
 		vpnsp = "private internet access"
 	}
+
+	if settings.isOpenVPNCustomConfig(r.env) { // retro compatibility
+		vpnsp = constants.Custom
+	}
+
 	settings.Name = vpnsp
 
 	return nil
@@ -199,3 +207,12 @@ func portsToString(ports []uint16) string {
 	}
 	return strings.Join(slice, ", ")
 }
+
+// isOpenVPNCustomConfig is for retro compatibility to set VPNSP=custom
+// if OPENVPN_CUSTOM_CONFIG is set.
+func (settings Provider) isOpenVPNCustomConfig(env params.Interface) (ok bool) {
+	s, _ := env.Get("VPN_TYPE")
+	isOpenVPN := s == constants.OpenVPN
+	s, _ = env.Get("OPENVPN_CUSTOM_CONFIG")
+	return isOpenVPN && s != ""
+}
diff --git a/internal/configuration/reader.go b/internal/configuration/reader.go
index dec6a503..a6b24045 100644
--- a/internal/configuration/reader.go
+++ b/internal/configuration/reader.go
@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/qdm12/gluetun/internal/models"
+	ovpnextract "github.com/qdm12/gluetun/internal/openvpn/extract"
 	"github.com/qdm12/golibs/logging"
 	"github.com/qdm12/golibs/params"
 	"github.com/qdm12/golibs/verification"
@@ -18,6 +19,7 @@ type reader struct {
 	env     params.Interface
 	logger  logging.Logger
 	regex   verification.Regex
+	ovpnExt ovpnextract.Interface
 }
 
 func newReader(env params.Interface,
@@ -27,6 +29,7 @@ func newReader(env params.Interface,
 		env:     env,
 		logger:  logger,
 		regex:   verification.NewRegex(),
+		ovpnExt: ovpnextract.New(),
 	}
 }
 
diff --git a/internal/configuration/secrets.go b/internal/configuration/secrets.go
index 67a45632..5c8118d4 100644
--- a/internal/configuration/secrets.go
+++ b/internal/configuration/secrets.go
@@ -51,22 +51,22 @@ func (r *reader) getFromEnvOrSecretFile(envKey string, compulsory bool, retroKey
 	file, fileErr := os.OpenFile(filepath, os.O_RDONLY, 0)
 	if os.IsNotExist(fileErr) {
 		if compulsory {
-			return "", envErr
+			return "", fmt.Errorf("environment variable %s: %w", envKey, envErr)
 		}
 		return "", nil
 	} else if fileErr != nil {
-		return "", fmt.Errorf("%w: %s", ErrReadSecretFile, fileErr)
+		return "", fmt.Errorf("%w: %s: %s", ErrReadSecretFile, filepath, fileErr)
 	}
 
 	b, err := io.ReadAll(file)
 	if err != nil {
-		return "", fmt.Errorf("%w: %s", ErrReadSecretFile, err)
+		return "", fmt.Errorf("%w: %s: %s", ErrReadSecretFile, filepath, err)
 	}
 
 	value = string(b)
 	value = cleanSuffix(value)
 	if compulsory && value == "" {
-		return "", ErrSecretFileIsEmpty
+		return "", fmt.Errorf("%s: %w", filepath, ErrSecretFileIsEmpty)
 	}
 
 	return value, nil
diff --git a/internal/configuration/selection.go b/internal/configuration/selection.go
index bb1ce424..352dfa7d 100644
--- a/internal/configuration/selection.go
+++ b/internal/configuration/selection.go
@@ -106,6 +106,7 @@ func (selection ServerSelection) toLines() (lines []string) {
 }
 
 type OpenVPNSelection struct {
+	ConfFile   string `json:"conf_file"`         // Custom configuration file path
 	TCP        bool   `json:"tcp"`               // UDP if TCP is false
 	CustomPort uint16 `json:"custom_port"`       // HideMyAss, Mullvad, PIA, ProtonVPN, Windscribe
 	EncPreset  string `json:"encryption_preset"` // PIA - needed to get the port number
@@ -114,6 +115,10 @@ type OpenVPNSelection struct {
 func (settings *OpenVPNSelection) lines() (lines []string) {
 	lines = append(lines, lastIndent+"OpenVPN selection:")
 
+	if settings.ConfFile != "" {
+		lines = append(lines, indent+lastIndent+"Custom configuration file: "+settings.ConfFile)
+	}
+
 	lines = append(lines, indent+lastIndent+"Protocol: "+protoToString(settings.TCP))
 
 	if settings.CustomPort != 0 {
diff --git a/internal/configuration/vpn.go b/internal/configuration/vpn.go
index 7056fb33..d09b182e 100644
--- a/internal/configuration/vpn.go
+++ b/internal/configuration/vpn.go
@@ -58,10 +58,8 @@ func (settings *VPN) read(r reader) (err error) {
 	}
 	settings.Type = vpnType
 
-	if !settings.isOpenVPNCustomConfig(r.env) {
-		if err := settings.Provider.read(r, vpnType); err != nil {
-			return fmt.Errorf("%w: %s", errReadProviderSettings, err)
-		}
+	if err := settings.Provider.read(r, vpnType); err != nil {
+		return fmt.Errorf("%w: %s", errReadProviderSettings, err)
 	}
 
 	switch settings.Type {
@@ -79,19 +77,3 @@ func (settings *VPN) read(r reader) (err error) {
 
 	return nil
 }
-
-func (settings VPN) isOpenVPNCustomConfig(env params.Interface) (ok bool) {
-	if settings.Type != constants.OpenVPN {
-		return false
-	}
-	s, err := env.Get("OPENVPN_CUSTOM_CONFIG")
-	return err == nil && s != ""
-}
-
-func (settings VPN) VPNInterface() (intf string) {
-	if settings.Type == constants.Wireguard {
-		return settings.Wireguard.Interface
-	}
-	// OpenVPN
-	return settings.OpenVPN.Interface
-}
diff --git a/internal/constants/vpn.go b/internal/constants/vpn.go
index 9af18ec7..80b245ef 100644
--- a/internal/constants/vpn.go
+++ b/internal/constants/vpn.go
@@ -6,6 +6,9 @@ const (
 )
 
 const (
+	// Custom is the VPN provider name for custom
+	// VPN configurations.
+	Custom = "custom"
 	// Cyberghost is a VPN provider.
 	Cyberghost = "cyberghost"
 	// Fastestvpn is a VPN provider.
diff --git a/internal/openvpn/custom/custom.go b/internal/openvpn/custom/custom.go
deleted file mode 100644
index 62c4be52..00000000
--- a/internal/openvpn/custom/custom.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package custom
-
-import (
-	"errors"
-	"fmt"
-
-	"github.com/qdm12/gluetun/internal/configuration"
-	"github.com/qdm12/gluetun/internal/models"
-)
-
-var (
-	ErrReadCustomConfig  = errors.New("cannot read custom configuration file")
-	ErrExtractConnection = errors.New("cannot extract connection from custom configuration file")
-)
-
-func BuildConfig(settings configuration.OpenVPN) (
-	lines []string, connection models.Connection, intf string, err error) {
-	lines, err = readCustomConfigLines(settings.Config)
-	if err != nil {
-		return nil, connection, "", fmt.Errorf("%w: %s", ErrReadCustomConfig, err)
-	}
-
-	connection, intf, err = extractDataFromLines(lines)
-	if err != nil {
-		return nil, connection, "", fmt.Errorf("%w: %s", ErrExtractConnection, err)
-	}
-
-	if intf == "" {
-		intf = settings.Interface
-	}
-
-	lines = modifyCustomConfig(lines, settings, connection, intf)
-
-	return lines, connection, intf, nil
-}
diff --git a/internal/openvpn/custom/custom_test.go b/internal/openvpn/custom/custom_test.go
deleted file mode 100644
index 34de0a89..00000000
--- a/internal/openvpn/custom/custom_test.go
+++ /dev/null
@@ -1,67 +0,0 @@
-package custom
-
-import (
-	"net"
-	"os"
-	"testing"
-
-	"github.com/qdm12/gluetun/internal/configuration"
-	"github.com/qdm12/gluetun/internal/constants"
-	"github.com/qdm12/gluetun/internal/models"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-func Test_BuildConfig(t *testing.T) {
-	t.Parallel()
-
-	file, err := os.CreateTemp("", "")
-	require.NoError(t, err)
-	defer removeFile(t, file.Name())
-	defer file.Close()
-
-	_, err = file.WriteString("remote 1.9.8.7\nkeep me\ncipher remove")
-	require.NoError(t, err)
-
-	err = file.Close()
-	require.NoError(t, err)
-
-	settings := configuration.OpenVPN{
-		Cipher:    "cipher",
-		MSSFix:    999,
-		Config:    file.Name(),
-		Interface: "tun0",
-	}
-
-	lines, connection, intf, err := BuildConfig(settings)
-	assert.NoError(t, err)
-
-	expectedLines := []string{
-		"keep me",
-		"proto udp",
-		"remote 1.9.8.7 1194",
-		"dev tun0",
-		"mute-replay-warnings",
-		"auth-nocache",
-		"pull-filter ignore \"auth-token\"",
-		"auth-retry nointeract",
-		"suppress-timestamps",
-		"verb 0",
-		"data-ciphers-fallback cipher",
-		"data-ciphers cipher",
-		"mssfix 999",
-		"pull-filter ignore \"route-ipv6\"",
-		"pull-filter ignore \"ifconfig-ipv6\"",
-		"user ",
-	}
-	assert.Equal(t, expectedLines, lines)
-
-	expectedConnection := models.Connection{
-		IP:       net.IPv4(1, 9, 8, 7),
-		Port:     1194,
-		Protocol: constants.UDP,
-	}
-	assert.Equal(t, expectedConnection, connection)
-
-	assert.Equal(t, "tun0", intf)
-}
diff --git a/internal/openvpn/extract/data.go b/internal/openvpn/extract/data.go
new file mode 100644
index 00000000..b5fcc526
--- /dev/null
+++ b/internal/openvpn/extract/data.go
@@ -0,0 +1,29 @@
+package extract
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+var (
+	ErrRead              = errors.New("cannot read file")
+	ErrExtractConnection = errors.New("cannot extract connection from file")
+)
+
+// Data extracts the lines and connection from the OpenVPN configuration file.
+func (e *Extractor) Data(filepath string) (lines []string,
+	connection models.Connection, err error) {
+	lines, err = readCustomConfigLines(filepath)
+	if err != nil {
+		return nil, connection, fmt.Errorf("%w: %s", ErrRead, err)
+	}
+
+	connection, err = extractDataFromLines(lines)
+	if err != nil {
+		return nil, connection, fmt.Errorf("%w: %s", ErrExtractConnection, err)
+	}
+
+	return lines, connection, nil
+}
diff --git a/internal/openvpn/custom/extract.go b/internal/openvpn/extract/extract.go
similarity index 68%
rename from internal/openvpn/custom/extract.go
rename to internal/openvpn/extract/extract.go
index 1e022a83..19edd5f1 100644
--- a/internal/openvpn/custom/extract.go
+++ b/internal/openvpn/extract/extract.go
@@ -1,4 +1,4 @@
-package custom
+package extract
 
 import (
 	"errors"
@@ -16,23 +16,22 @@ var (
 )
 
 func extractDataFromLines(lines []string) (
-	connection models.Connection, intf string, err error) {
+	connection models.Connection, err error) {
 	for i, line := range lines {
-		ip, port, protocol, intfFound, err := extractDataFromLine(line)
+		ip, port, protocol, err := extractDataFromLine(line)
 		if err != nil {
-			return connection, "", fmt.Errorf("on line %d: %w", i+1, err)
+			return connection, fmt.Errorf("on line %d: %w", i+1, err)
 		}
 
-		intf = intfFound
 		connection.UpdateEmptyWith(ip, port, protocol)
 
-		if connection.Protocol != "" && connection.IP != nil && intf != "" {
+		if connection.Protocol != "" && connection.IP != nil {
 			break
 		}
 	}
 
 	if connection.IP == nil {
-		return connection, "", errRemoteLineNotFound
+		return connection, errRemoteLineNotFound
 	}
 
 	if connection.Protocol == "" {
@@ -46,41 +45,33 @@ func extractDataFromLines(lines []string) (
 		}
 	}
 
-	return connection, intf, nil
+	return connection, nil
 }
 
 var (
 	errExtractProto  = errors.New("failed extracting protocol from proto line")
 	errExtractRemote = errors.New("failed extracting from remote line")
-	errExtractDev    = errors.New("failed extracting network interface from dev line")
 )
 
 func extractDataFromLine(line string) (
-	ip net.IP, port uint16, protocol, intf string, err error) {
+	ip net.IP, port uint16, protocol string, err error) {
 	switch {
 	case strings.HasPrefix(line, "proto "):
 		protocol, err = extractProto(line)
 		if err != nil {
-			return nil, 0, "", "", fmt.Errorf("%w: %s", errExtractProto, err)
+			return nil, 0, "", fmt.Errorf("%w: %s", errExtractProto, err)
 		}
-		return nil, 0, protocol, "", nil
+		return nil, 0, protocol, nil
 
 	case strings.HasPrefix(line, "remote "):
 		ip, port, protocol, err = extractRemote(line)
 		if err != nil {
-			return nil, 0, "", "", fmt.Errorf("%w: %s", errExtractRemote, err)
+			return nil, 0, "", fmt.Errorf("%w: %s", errExtractRemote, err)
 		}
-		return ip, port, protocol, "", nil
-
-	case strings.HasPrefix(line, "dev "):
-		intf, err = extractInterfaceFromLine(line)
-		if err != nil {
-			return nil, 0, "", "", fmt.Errorf("%w: %s", errExtractDev, err)
-		}
-		return nil, 0, "", intf, nil
+		return ip, port, protocol, nil
 	}
 
-	return nil, 0, "", "", nil
+	return nil, 0, "", nil
 }
 
 var (
@@ -147,16 +138,3 @@ func extractRemote(line string) (ip net.IP, port uint16,
 
 	return ip, port, protocol, nil
 }
-
-var (
-	errDevLineFieldsCount = errors.New("dev line has not 2 fields as expected")
-)
-
-func extractInterfaceFromLine(line string) (intf string, err error) {
-	fields := strings.Fields(line)
-	if len(fields) != 2 { //nolint:gomnd
-		return "", fmt.Errorf("%w: %s", errDevLineFieldsCount, line)
-	}
-
-	return fields[1], nil
-}
diff --git a/internal/openvpn/custom/extract_test.go b/internal/openvpn/extract/extract_test.go
similarity index 82%
rename from internal/openvpn/custom/extract_test.go
rename to internal/openvpn/extract/extract_test.go
index 24ea8749..b5191422 100644
--- a/internal/openvpn/custom/extract_test.go
+++ b/internal/openvpn/extract/extract_test.go
@@ -1,4 +1,4 @@
-package custom
+package extract
 
 import (
 	"errors"
@@ -17,7 +17,6 @@ func Test_extractDataFromLines(t *testing.T) {
 	testCases := map[string]struct {
 		lines      []string
 		connection models.Connection
-		intf       string
 		err        error
 	}{
 		"success": {
@@ -27,7 +26,6 @@ func Test_extractDataFromLines(t *testing.T) {
 				Port:     1194,
 				Protocol: constants.TCP,
 			},
-			intf: "tun6",
 		},
 		"extraction error": {
 			lines: []string{"bla bla", "proto bad", "remote 1.2.3.4 1194 tcp"},
@@ -71,7 +69,7 @@ func Test_extractDataFromLines(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
-			connection, intf, err := extractDataFromLines(testCase.lines)
+			connection, err := extractDataFromLines(testCase.lines)
 
 			if testCase.err != nil {
 				require.Error(t, err)
@@ -81,7 +79,6 @@ func Test_extractDataFromLines(t *testing.T) {
 			}
 
 			assert.Equal(t, testCase.connection, connection)
-			assert.Equal(t, testCase.intf, intf)
 		})
 	}
 }
@@ -94,7 +91,6 @@ func Test_extractDataFromLine(t *testing.T) {
 		ip       net.IP
 		port     uint16
 		protocol string
-		intf     string
 		isErr    error
 	}{
 		"irrelevant line": {
@@ -108,14 +104,6 @@ func Test_extractDataFromLine(t *testing.T) {
 			line:     "proto tcp",
 			protocol: constants.TCP,
 		},
-		"extract intf error": {
-			line:  "dev ",
-			isErr: errExtractDev,
-		},
-		"extract intf success": {
-			line: "dev tun3",
-			intf: "tun3",
-		},
 		"extract remote error": {
 			line:  "remote bad",
 			isErr: errExtractRemote,
@@ -133,7 +121,7 @@ func Test_extractDataFromLine(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
-			ip, port, protocol, intf, err := extractDataFromLine(testCase.line)
+			ip, port, protocol, err := extractDataFromLine(testCase.line)
 
 			if testCase.isErr != nil {
 				assert.ErrorIs(t, err, testCase.isErr)
@@ -144,7 +132,6 @@ func Test_extractDataFromLine(t *testing.T) {
 			assert.Equal(t, testCase.ip, ip)
 			assert.Equal(t, testCase.port, port)
 			assert.Equal(t, testCase.protocol, protocol)
-			assert.Equal(t, testCase.intf, intf)
 		})
 	}
 }
@@ -273,44 +260,3 @@ func Test_extractRemote(t *testing.T) {
 		})
 	}
 }
-
-func Test_extractInterface(t *testing.T) {
-	t.Parallel()
-
-	testCases := map[string]struct {
-		line string
-		intf string
-		err  error
-	}{
-		"found": {
-			line: "dev tun3",
-			intf: "tun3",
-		},
-		"not enough fields": {
-			line: "dev ",
-			err:  errors.New("dev line has not 2 fields as expected: dev "),
-		},
-		"too many fields": {
-			line: "dev one two",
-			err:  errors.New("dev line has not 2 fields as expected: dev one two"),
-		},
-	}
-
-	for name, testCase := range testCases {
-		testCase := testCase
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			intf, err := extractInterfaceFromLine(testCase.line)
-
-			if testCase.err != nil {
-				require.Error(t, err)
-				assert.Equal(t, testCase.err.Error(), err.Error())
-			} else {
-				assert.NoError(t, err)
-			}
-
-			assert.Equal(t, testCase.intf, intf)
-		})
-	}
-}
diff --git a/internal/openvpn/extract/extractor.go b/internal/openvpn/extract/extractor.go
new file mode 100644
index 00000000..a40614aa
--- /dev/null
+++ b/internal/openvpn/extract/extractor.go
@@ -0,0 +1,18 @@
+package extract
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+var _ Interface = (*Extractor)(nil)
+
+type Interface interface {
+	Data(filepath string) (lines []string,
+		connection models.Connection, err error)
+}
+
+type Extractor struct{}
+
+func New() *Extractor {
+	return new(Extractor)
+}
diff --git a/internal/openvpn/custom/helpers_test.go b/internal/openvpn/extract/helpers_test.go
similarity index 92%
rename from internal/openvpn/custom/helpers_test.go
rename to internal/openvpn/extract/helpers_test.go
index b6f6df2e..41c6c174 100644
--- a/internal/openvpn/custom/helpers_test.go
+++ b/internal/openvpn/extract/helpers_test.go
@@ -1,4 +1,4 @@
-package custom
+package extract
 
 import (
 	"os"
diff --git a/internal/openvpn/custom/read.go b/internal/openvpn/extract/read.go
similarity index 95%
rename from internal/openvpn/custom/read.go
rename to internal/openvpn/extract/read.go
index 8e2ee03d..9da84948 100644
--- a/internal/openvpn/custom/read.go
+++ b/internal/openvpn/extract/read.go
@@ -1,4 +1,4 @@
-package custom
+package extract
 
 import (
 	"io"
diff --git a/internal/openvpn/custom/read_test.go b/internal/openvpn/extract/read_test.go
similarity index 97%
rename from internal/openvpn/custom/read_test.go
rename to internal/openvpn/extract/read_test.go
index bc050427..e2bb2981 100644
--- a/internal/openvpn/custom/read_test.go
+++ b/internal/openvpn/extract/read_test.go
@@ -1,4 +1,4 @@
-package custom
+package extract
 
 import (
 	"os"
diff --git a/internal/provider/custom/connection.go b/internal/provider/custom/connection.go
new file mode 100644
index 00000000..6713c02b
--- /dev/null
+++ b/internal/provider/custom/connection.go
@@ -0,0 +1,38 @@
+package custom
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/provider/utils"
+)
+
+var (
+	ErrVPNTypeNotSupported = errors.New("VPN type not supported for custom provider")
+	ErrExtractConnection   = errors.New("cannot extract connection")
+)
+
+// GetConnection gets the connection from the OpenVPN configuration file.
+func (p *Provider) GetConnection(selection configuration.ServerSelection) (
+	connection models.Connection, err error) {
+	if selection.VPN != constants.OpenVPN {
+		return connection, fmt.Errorf("%w: %s", ErrVPNTypeNotSupported, selection.VPN)
+	}
+
+	_, connection, err = p.extractor.Data(selection.OpenVPN.ConfFile)
+	if err != nil {
+		return connection, fmt.Errorf("%w: %s", ErrExtractConnection, err)
+	}
+
+	connection.Port = getPort(connection.Port, selection)
+
+	return connection, nil
+}
+
+// Port found is overridden by custom port set with `PORT` or `WIREGUARD_PORT`.
+func getPort(foundPort uint16, selection configuration.ServerSelection) (port uint16) {
+	return utils.GetPort(selection, foundPort, foundPort, foundPort)
+}
diff --git a/internal/openvpn/custom/modify.go b/internal/provider/custom/openvpnconf.go
similarity index 67%
rename from internal/openvpn/custom/modify.go
rename to internal/provider/custom/openvpnconf.go
index 490b1e40..82eae215 100644
--- a/internal/openvpn/custom/modify.go
+++ b/internal/provider/custom/openvpnconf.go
@@ -1,6 +1,8 @@
 package custom
 
 import (
+	"errors"
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -10,13 +12,27 @@ import (
 	"github.com/qdm12/gluetun/internal/provider/utils"
 )
 
-func modifyCustomConfig(lines []string, settings configuration.OpenVPN,
-	connection models.Connection, intf string) (modified []string) {
+var ErrExtractData = errors.New("failed extracting information from custom configuration file")
+
+func (p *Provider) BuildConf(connection models.Connection,
+	settings configuration.OpenVPN) (lines []string, err error) {
+	lines, _, err = p.extractor.Data(settings.ConfFile)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %s", ErrExtractData, err)
+	}
+
+	lines = modifyConfig(lines, connection, settings)
+
+	return lines, nil
+}
+
+func modifyConfig(lines []string, connection models.Connection,
+	settings configuration.OpenVPN) (modified []string) {
 	// Remove some lines
 	for _, line := range lines {
 		switch {
-		case strings.HasPrefix(line, "up "),
-			strings.HasPrefix(line, "down "),
+		case
+			line == "",
 			strings.HasPrefix(line, "verb "),
 			strings.HasPrefix(line, "auth-user-pass "),
 			strings.HasPrefix(line, "user "),
@@ -36,7 +52,7 @@ func modifyCustomConfig(lines []string, settings configuration.OpenVPN,
 	// Add values
 	modified = append(modified, connection.OpenVPNProtoLine())
 	modified = append(modified, connection.OpenVPNRemoteLine())
-	modified = append(modified, "dev "+intf)
+	modified = append(modified, "dev "+settings.Interface)
 	modified = append(modified, "mute-replay-warnings")
 	modified = append(modified, "auth-nocache")
 	modified = append(modified, "pull-filter ignore \"auth-token\"") // prevent auth failed loop
@@ -63,5 +79,23 @@ func modifyCustomConfig(lines []string, settings configuration.OpenVPN,
 		modified = append(modified, "user "+settings.ProcUser)
 	}
 
-	return modified
+	modified = append(modified, "") // trailing line
+
+	return uniqueLines(modified)
+}
+
+func uniqueLines(lines []string) (unique []string) {
+	seen := make(map[string]struct{}, len(lines))
+	unique = make([]string, 0, len(lines))
+
+	for _, line := range lines {
+		_, ok := seen[line]
+		if ok {
+			continue
+		}
+		seen[line] = struct{}{}
+		unique = append(unique, line)
+	}
+
+	return unique
 }
diff --git a/internal/openvpn/custom/modify_test.go b/internal/provider/custom/openvpnconf_test.go
similarity index 82%
rename from internal/openvpn/custom/modify_test.go
rename to internal/provider/custom/openvpnconf_test.go
index 493e7c41..702b40e4 100644
--- a/internal/openvpn/custom/modify_test.go
+++ b/internal/provider/custom/openvpnconf_test.go
@@ -10,14 +10,13 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func Test_modifyCustomConfig(t *testing.T) {
+func Test_modifyConfig(t *testing.T) {
 	t.Parallel()
 
 	testCases := map[string]struct {
 		lines      []string
 		settings   configuration.OpenVPN
 		connection models.Connection
-		intf       string
 		modified   []string
 	}{
 		"mixed": {
@@ -26,24 +25,26 @@ func Test_modifyCustomConfig(t *testing.T) {
 				"proto tcp",
 				"remote 5.5.5.5",
 				"cipher bla",
+				"",
 				"tun-ipv6",
 				"keep me here",
 				"auth bla",
 			},
 			settings: configuration.OpenVPN{
-				User:     "user",
-				Cipher:   "cipher",
-				Auth:     "auth",
-				MSSFix:   1000,
-				ProcUser: "procuser",
+				User:      "user",
+				Cipher:    "cipher",
+				Auth:      "auth",
+				MSSFix:    1000,
+				ProcUser:  "procuser",
+				Interface: "tun3",
 			},
 			connection: models.Connection{
 				IP:       net.IPv4(1, 2, 3, 4),
 				Port:     1194,
 				Protocol: constants.UDP,
 			},
-			intf: "tun3",
 			modified: []string{
+				"up bla",
 				"keep me here",
 				"proto udp",
 				"remote 1.2.3.4 1194",
@@ -62,6 +63,7 @@ func Test_modifyCustomConfig(t *testing.T) {
 				"pull-filter ignore \"route-ipv6\"",
 				"pull-filter ignore \"ifconfig-ipv6\"",
 				"user procuser",
+				"",
 			},
 		},
 	}
@@ -71,8 +73,8 @@ func Test_modifyCustomConfig(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
-			modified := modifyCustomConfig(testCase.lines,
-				testCase.settings, testCase.connection, testCase.intf)
+			modified := modifyConfig(testCase.lines,
+				testCase.connection, testCase.settings)
 
 			assert.Equal(t, testCase.modified, modified)
 		})
diff --git a/internal/provider/custom/provider.go b/internal/provider/custom/provider.go
new file mode 100644
index 00000000..28dab95d
--- /dev/null
+++ b/internal/provider/custom/provider.go
@@ -0,0 +1,19 @@
+package custom
+
+import (
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/openvpn/extract"
+	"github.com/qdm12/gluetun/internal/provider/utils"
+)
+
+type Provider struct {
+	extractor extract.Interface
+	utils.NoPortForwarder
+}
+
+func New() *Provider {
+	return &Provider{
+		extractor:       extract.New(),
+		NoPortForwarder: utils.NewNoPortForwarding(constants.Custom),
+	}
+}
diff --git a/internal/provider/cyberghost/openvpnconf.go b/internal/provider/cyberghost/openvpnconf.go
index 231f5df8..37cf2767 100644
--- a/internal/provider/cyberghost/openvpnconf.go
+++ b/internal/provider/cyberghost/openvpnconf.go
@@ -11,7 +11,7 @@ import (
 )
 
 func (c *Cyberghost) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -87,5 +87,5 @@ func (c *Cyberghost) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/fastestvpn/openvpnconf.go b/internal/provider/fastestvpn/openvpnconf.go
index 105f434f..62fc7cc3 100644
--- a/internal/provider/fastestvpn/openvpnconf.go
+++ b/internal/provider/fastestvpn/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (f *Fastestvpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -76,5 +76,5 @@ func (f *Fastestvpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/hidemyass/openvpnconf.go b/internal/provider/hidemyass/openvpnconf.go
index 6b898fec..59592502 100644
--- a/internal/provider/hidemyass/openvpnconf.go
+++ b/internal/provider/hidemyass/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (h *HideMyAss) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -75,5 +75,5 @@ func (h *HideMyAss) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/ipvanish/openvpnconf.go b/internal/provider/ipvanish/openvpnconf.go
index 5065204f..afd7ab6f 100644
--- a/internal/provider/ipvanish/openvpnconf.go
+++ b/internal/provider/ipvanish/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (i *Ipvanish) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -68,5 +68,5 @@ func (i *Ipvanish) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/ivpn/openvpnconf.go b/internal/provider/ivpn/openvpnconf.go
index 41307365..e72ee5c5 100644
--- a/internal/provider/ivpn/openvpnconf.go
+++ b/internal/provider/ivpn/openvpnconf.go
@@ -11,7 +11,7 @@ import (
 )
 
 func (i *Ivpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -77,5 +77,5 @@ func (i *Ivpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/mullvad/openvpnconf.go b/internal/provider/mullvad/openvpnconf.go
index 20449880..15fab6c6 100644
--- a/internal/provider/mullvad/openvpnconf.go
+++ b/internal/provider/mullvad/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (m *Mullvad) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -83,5 +83,5 @@ func (m *Mullvad) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/nordvpn/openvpnconf.go b/internal/provider/nordvpn/openvpnconf.go
index dd926ba1..d64b4ece 100644
--- a/internal/provider/nordvpn/openvpnconf.go
+++ b/internal/provider/nordvpn/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (n *Nordvpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -81,5 +81,5 @@ func (n *Nordvpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/privado/openvpnconf.go b/internal/provider/privado/openvpnconf.go
index 0c0af77e..cb20ffd4 100644
--- a/internal/provider/privado/openvpnconf.go
+++ b/internal/provider/privado/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (p *Privado) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -70,5 +70,5 @@ func (p *Privado) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/privateinternetaccess/openvpnconf.go b/internal/provider/privateinternetaccess/openvpnconf.go
index 78222f67..400b4d99 100644
--- a/internal/provider/privateinternetaccess/openvpnconf.go
+++ b/internal/provider/privateinternetaccess/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (p *PIA) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	var defaultCipher, defaultAuth, X509CRL, certificate string
 	switch settings.EncPreset {
 	case constants.PIAEncryptionPresetNormal:
@@ -93,5 +93,5 @@ func (p *PIA) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/privatevpn/openvpnconf.go b/internal/provider/privatevpn/openvpnconf.go
index fdb3194f..8cde04be 100644
--- a/internal/provider/privatevpn/openvpnconf.go
+++ b/internal/provider/privatevpn/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (p *Privatevpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES128gcm
 	}
@@ -73,5 +73,5 @@ func (p *Privatevpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/protonvpn/openvpnconf.go b/internal/provider/protonvpn/openvpnconf.go
index 357b4e0c..1828f13c 100644
--- a/internal/provider/protonvpn/openvpnconf.go
+++ b/internal/provider/protonvpn/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (p *Protonvpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -80,5 +80,5 @@ func (p *Protonvpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/provider.go b/internal/provider/provider.go
index 6ede2f80..c0fa2d7c 100644
--- a/internal/provider/provider.go
+++ b/internal/provider/provider.go
@@ -11,6 +11,7 @@ import (
 	"github.com/qdm12/gluetun/internal/configuration"
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/provider/custom"
 	"github.com/qdm12/gluetun/internal/provider/cyberghost"
 	"github.com/qdm12/gluetun/internal/provider/fastestvpn"
 	"github.com/qdm12/gluetun/internal/provider/hidemyass"
@@ -34,7 +35,7 @@ import (
 // Provider contains methods to read and modify the openvpn configuration to connect as a client.
 type Provider interface {
 	GetConnection(selection configuration.ServerSelection) (connection models.Connection, err error)
-	BuildConf(connection models.Connection, settings configuration.OpenVPN) (lines []string)
+	BuildConf(connection models.Connection, settings configuration.OpenVPN) (lines []string, err error)
 	PortForwarder
 }
 
@@ -50,6 +51,8 @@ type PortForwarder interface {
 func New(provider string, allServers models.AllServers, timeNow func() time.Time) Provider {
 	randSource := rand.NewSource(timeNow().UnixNano())
 	switch provider {
+	case constants.Custom:
+		return custom.New()
 	case constants.Cyberghost:
 		return cyberghost.New(allServers.Cyberghost.Servers, randSource)
 	case constants.Fastestvpn:
diff --git a/internal/provider/purevpn/openvpnconf.go b/internal/provider/purevpn/openvpnconf.go
index db83de4a..58d3ee22 100644
--- a/internal/provider/purevpn/openvpnconf.go
+++ b/internal/provider/purevpn/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (p *Purevpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256gcm
 	}
@@ -84,5 +84,5 @@ func (p *Purevpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/surfshark/openvpnconf.go b/internal/provider/surfshark/openvpnconf.go
index 58b5892f..6299406c 100644
--- a/internal/provider/surfshark/openvpnconf.go
+++ b/internal/provider/surfshark/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (s *Surfshark) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256gcm
 	}
@@ -78,5 +78,5 @@ func (s *Surfshark) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/torguard/openvpnconf.go b/internal/provider/torguard/openvpnconf.go
index 8ea3a6aa..27924df6 100644
--- a/internal/provider/torguard/openvpnconf.go
+++ b/internal/provider/torguard/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (t *Torguard) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256gcm
 	}
@@ -84,5 +84,5 @@ func (t *Torguard) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/vpnunlimited/openvpnconf.go b/internal/provider/vpnunlimited/openvpnconf.go
index f2c65623..2f3168db 100644
--- a/internal/provider/vpnunlimited/openvpnconf.go
+++ b/internal/provider/vpnunlimited/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (p *Provider) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	lines = []string{
 		"client",
 		"dev " + settings.Interface,
@@ -71,5 +71,5 @@ func (p *Provider) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/vyprvpn/openvpnconf.go b/internal/provider/vyprvpn/openvpnconf.go
index 1d8e4da4..a97229b1 100644
--- a/internal/provider/vyprvpn/openvpnconf.go
+++ b/internal/provider/vyprvpn/openvpnconf.go
@@ -10,7 +10,7 @@ import (
 )
 
 func (v *Vyprvpn) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -65,5 +65,5 @@ func (v *Vyprvpn) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/provider/windscribe/openvpnconf.go b/internal/provider/windscribe/openvpnconf.go
index 33921c52..9e8afb4f 100644
--- a/internal/provider/windscribe/openvpnconf.go
+++ b/internal/provider/windscribe/openvpnconf.go
@@ -11,7 +11,7 @@ import (
 )
 
 func (w *Windscribe) BuildConf(connection models.Connection,
-	settings configuration.OpenVPN) (lines []string) {
+	settings configuration.OpenVPN) (lines []string, err error) {
 	if settings.Cipher == "" {
 		settings.Cipher = constants.AES256cbc
 	}
@@ -81,5 +81,5 @@ func (w *Windscribe) BuildConf(connection models.Connection,
 
 	lines = append(lines, "")
 
-	return lines
+	return lines, nil
 }
diff --git a/internal/vpn/openvpn.go b/internal/vpn/openvpn.go
index 0250af38..48d3a537 100644
--- a/internal/vpn/openvpn.go
+++ b/internal/vpn/openvpn.go
@@ -7,15 +7,14 @@ import (
 
 	"github.com/qdm12/gluetun/internal/configuration"
 	"github.com/qdm12/gluetun/internal/firewall"
-	"github.com/qdm12/gluetun/internal/models"
 	"github.com/qdm12/gluetun/internal/openvpn"
-	"github.com/qdm12/gluetun/internal/openvpn/custom"
 	"github.com/qdm12/gluetun/internal/provider"
 	"github.com/qdm12/golibs/command"
 	"github.com/qdm12/golibs/logging"
 )
 
 var (
+	errServerConn  = errors.New("failed finding a valid server connection")
 	errBuildConfig = errors.New("failed building configuration")
 	errWriteConfig = errors.New("failed writing configuration to file")
 	errWriteAuth   = errors.New("failed writing auth to file")
@@ -28,18 +27,12 @@ func setupOpenVPN(ctx context.Context, fw firewall.VPNConnectionSetter,
 	openvpnConf openvpn.Interface, providerConf provider.Provider,
 	settings configuration.VPN, starter command.Starter, logger logging.Logger) (
 	runner vpnRunner, serverName string, err error) {
-	var connection models.Connection
-	var netInterface string
-	var lines []string
-	if settings.OpenVPN.Config == "" {
-		netInterface = settings.OpenVPN.Interface
-		connection, err = providerConf.GetConnection(settings.Provider.ServerSelection)
-		if err == nil {
-			lines = providerConf.BuildConf(connection, settings.OpenVPN)
-		}
-	} else {
-		lines, connection, netInterface, err = custom.BuildConfig(settings.OpenVPN)
+	connection, err := providerConf.GetConnection(settings.Provider.ServerSelection)
+	if err != nil {
+		return nil, "", fmt.Errorf("%w: %s", errServerConn, err)
 	}
+
+	lines, err := providerConf.BuildConf(connection, settings.OpenVPN)
 	if err != nil {
 		return nil, "", fmt.Errorf("%w: %s", errBuildConfig, err)
 	}
@@ -55,7 +48,7 @@ func setupOpenVPN(ctx context.Context, fw firewall.VPNConnectionSetter,
 		}
 	}
 
-	if err := fw.SetVPNConnection(ctx, connection, netInterface); err != nil {
+	if err := fw.SetVPNConnection(ctx, connection, settings.OpenVPN.Interface); err != nil {
 		return nil, "", fmt.Errorf("%w: %s", errFirewall, err)
 	}
 
diff --git a/maintenance.md b/maintenance.md
index a6517868..8aaef98b 100644
--- a/maintenance.md
+++ b/maintenance.md
@@ -28,6 +28,7 @@
 - Gluetun entire logs available at control server, maybe in structured format
 - Authentication with the control server
 - Get announcement from Github file
+- Support multiple connections in custom ovpn
 
 ## Gluetun V4
 
@@ -47,4 +48,7 @@
 - Change `VPNSP` to `VPN_SERVICE_PROVIDER`
 - Change `REGION` (etc.) to `SERVER_REGIONS`
 - Remove `PUBLICIP_FILE`
+- Remove retro-compatibility where OPENVPN_CONFIG != "" implies VPNSP = "custom"
+ and set `OPENVPN_CUSTOM_CONFIG` default to `/gluetun/custom.ovpn`
 - Split servers.json and compress it
+- Use relative paths everywhere instead of absolute