Lan game impossible

[The 11th plague]

Today me and a friend of mine tried to play a lan game using Warzone 2.3.5, and it seemed like we couldn't be online at the same time. We are were using a XP pc and a Win7 laptop connected by a router with UPNP activated. At times we got the 2100 port error, but the problems seem to show up when we try to connect to each other, or host 2 games at the same time. People from outside were able to connect to our pcs, and we could access some other games in the lobby.

EDIT: it seems to work using the ip address. The 7 box can host a game sometimes, but it gets a lot of 2100 errors.

BTW now I get another strange problem on the Win7 laptop. When I open Warzone, the mouse gets stuck on the screen, and the game icon don't appear until I ctrl-alt-canc the system.

[Buginator]

If you have a really good router, then it can work via the lobby, but most people have crappy routers, and must use the direct IP to join the games.

The mouse shouldn't get stuck, this sounds like a conflict of some kind, but can't tell for sure without more information.