feat(ipv6): prefer IPv6 endpoints when IPv6 is supported

internal/provider/utils/connection.go

@@ -2,6 +2,7 @@ package utils
 
 import (
 	"fmt"
+	"slices"
 
 	"github.com/qdm12/gluetun/internal/configuration/settings"
 	"github.com/qdm12/gluetun/internal/constants/vpn"
@@ -75,5 +76,18 @@ func GetConnection(provider string,
 		}
 	}
 
+	slices.SortStableFunc(connections, func(a, b models.Connection) int {
+		aIPv6 := a.IP.Is6()
+		bIPv6 := b.IP.Is6()
+		switch {
+		case aIPv6 && !bIPv6:
+			return -1
+		case !aIPv6 && bIPv6:
+			return 1
+		default:
+			return 0
+		}
+	})
+
 	return pickConnection(connections, selection, connPicker)
 }

internal/provider/utils/connection_test.go

@@ -124,8 +124,8 @@ func Test_GetConnection(t *testing.T) {
 					VPN: vpn.OpenVPN,
 					UDP: true,
 					IPs: []netip.Addr{
-						netip.IPv6Unspecified(),
 						netip.AddrFrom4([4]byte{1, 1, 1, 1}),
+						netip.IPv6Unspecified(),
 					},
 				},
 			},