I am trying to play Total War with my friends using the LAN side of the game as opposed to online play. The problem I have been having using Wireguard is that the game doesn't let me manually connect to a host using its host name or Wireguard IP address.
The games we make in the lobby don't show up either even though I can ping and otherwise connect to the other computers.
Is there a setting or configuration I need to do for the LAN game lobby to populate or broadcast to all of the wireguard peers?
Hmm not sure how the game communicates it could be broadcast, it could be multicast, you need to check what magic happens when a client searches for a other lan host and when one hosts a lan with tcpdump.
Multicast may can work although wireguard never supports this but it is complicated, you could add a route 244.0.0.0/4 to it, make sure the wgserver instance has checked the DSA multicast option, this counts also for the wireguard clients on the other side and then try avahi to populate discovery through the router ip, though the vpn software in the gl firmware is different than vanilla OpenWrt this may doesn't work in conjunction with the DSA multicast option.
If it is broadcast then it will not work and I doubt adding a route will fix that, only for multicast, because it expects you to be on the exact same subnet.
But that doesn't mean it is not possible, you have to look into layer 2 tunnels, gretap or vxlan this will allow them to join your network via dhcp exactly like home with all the multicast and broadcasting, you want to add this gre/vxlan tunnel inside wireguard or if you are more comfy with OpenVPN only OpenVPN since it can do L2 too or netbird.
Though i never used those without vlans, mainly i used them for vlans but i guess that is your best bet, it will not be easy, onemarcfifty has a few videos about this you can check on youtube.