Add contabo wan for ipv6 support

modules/nixos/contabo/wan/default.nix

@@ -0,0 +1,65 @@
+{
+  lib,
+  config,
+  ...
+}:
+with lib; let
+  cfg = config.modules.contabo.wan;
+in {
+  options.modules.contabo.wan = {
+    enable = mkEnableOption "Enable Contabo Cloud WAN interface configuration";
+
+    macAddress = mkOption {
+      type = types.str;
+      description = "MAC Address of the WAN interface";
+    };
+
+    ipAddresses = mkOption {
+      type = types.listOf types.str;
+      description = "List of IP Addresses on the WAN interface";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.network.networks."20-wan" = {
+      matchConfig = {
+        MACAddress = cfg.macAddress;
+      };
+      address = cfg.ipAddresses;
+      routes = [
+        {routeConfig.Gateway = "fe80::1";}
+        {routeConfig = {Destination = "172.31.1.1";};}
+        {
+          routeConfig = {
+            Gateway = "172.31.1.1";
+            GatewayOnLink = true;
+          };
+        }
+        {
+          routeConfig = {
+            Destination = "172.16.0.0/12";
+            Type = "unreachable";
+          };
+        }
+        {
+          routeConfig = {
+            Destination = "192.168.0.0/16";
+            Type = "unreachable";
+          };
+        }
+        {
+          routeConfig = {
+            Destination = "10.0.0.0/8";
+            Type = "unreachable";
+          };
+        }
+        {
+          routeConfig = {
+            Destination = "fc00::/7";
+            Type = "unreachable";
+          };
+        }
+      ];
+    };
+  };
+}