I have the same question. I tried to set up magic packet broadcast to x.x.x.255 IP address in port forwarding, but it’s not working, see my other post here.
Next workaround, I added a static IP binding to the MAC broadcast address of FF:FF:FF:FF:FF, so I could just forward UDP 7 port (for magic packet) to that IP address and trick the router into doing a MAC broadcast this way:
However that binding entry does not appear in the ARP table, probably because of the note above Mind the configured client has to reconnect the router to come into effect.
How do I add that binding to the ARP table persistently, and will that work?