WLAN is works the exact same as LAN so you should still be able to connect to the game, I would try connecting both via cable through the router, you may need to open some ports on the router, or change some setting in the game, because WLAN works the exact same as LAN except one doesn't haven't wires, lol.

So Try connecting both computers through the router with wires, if it still doesn't work, means there's either a port problem, or an ip problem, something with the router.