storage-ng/public-access-proxy: default gateway 172.22.99.4 on eth0

hosts/storage-ng/public-access-proxy/configuration.nix

@@ -21,7 +21,7 @@
   fileSystems."/" = { fsType = "rootfs"; device = "rootfs"; };
 
   networking.hostName = "public-access-proxy";
-  networking.defaultGateway = "172.22.99.4";
+  networking.defaultGateway = { address = "172.22.99.4"; interface = "eth0"; };
 
   # Set your time zone.
   time.timeZone = "Europe/Berlin";