apu: setup transport layout offloads for tailscale

hosts/apu/configuration.nix

@@ -2,7 +2,7 @@
 # your system. Help is availanodev";
 # https://search.nixos.org/options and in the NixOS manual (`nixos-help`).
 
-{ lib, pkgs, ... }:
+{ lib, pkgs, config, ... }:
 let
   services = {
     ssh = { tcp = [ 22 ]; };
@@ -205,6 +205,17 @@ in
     } // vlanNetworks;
   };
 
+  services.networkd-dispatcher = {
+    enable = true;
+    rules."50-tailscale" = {
+      onState = [ "routable" ];
+      script = ''
+        #!${pkgs.runtimeShell}
+        ${pkgs.ethtool}/bin/ethtool -K ${config.systemd.network.links."10-extern0".linkConfig.Name} rx-udp-gro-forwarding on rx-gro-list off
+      '';
+    };
+  };
+
   time.timeZone = "Europe/Helsinki";
 
   users.users.jokke = {