pkgs/openwrt/uci-config: add mtu hotfix

nix/pkgs/openwrt/uci-config.nix

@@ -294,6 +294,20 @@ in
 
   uci commit
 
+  # Add hotfixes for MTU settings
+  cat >/etc/hotplug.d/iface/99-mtu <<__MTU__
+  #!/bin/sh
+
+  ${concatMapStrings (net:
+    optionalString (config.site.net ? ${net} &&
+                    config.site.net.${net}.mtu != null) ''
+      if [ "\\\$ACTION" = ifup -a "\\\$INTERFACE" = ${net} ]; then
+        ip link set ${net} mtu ${toString config.site.net.${net}.mtu}
+      fi
+    '') (builtins.attrNames hostConfig.interfaces)
+   }
+  __MTU__
+
   ${optionalString hostConfig.wifiOnLink.enable ''
     # Cronjob that makes sure WiFi is only visible when server with all
     # the gateways is reachable