>> Why don't you send WOL directly over the internet? (You'll need to set up a permanent ARP record on the router.)

> Hm, so never tried something like that before actually, I think for OpenWrt I need to install arp packages.

No, you don't. Put this in /etc/firewall.user or /etc/rc.local (you can do it from UI) and forward a UDP port to 192.168.0.254 or whaterver subnet you're using:

  ip neigh add 192.168.0.254 lladdr ff:ff:ff:ff:ff:ff nud permanent dev br-lan extern_learn

PS:

Correction! /etc/rc.local isn't OK. The ARP record needs to be reloaded if br-lan interface is restarted, such as when changing other network settings in WebUI. So only /etc/firewall.user will do.

Thank you for the explanation!

The version in the OpenWrt didn't support the full command. Had to update to `ip-full`.

After the command was successful, I can see the entry in the `ip neigh` table.

Now digging around