First, don't triplepost (I assume it's you and irollgen having this issue).
Second, check out these things. Firewall, it might me blocking LFS connection, disable it for testing, it you get the game working, you can enable it again. Since you both seem to have a router, I'd like to point out something about the port forwarding. It's only the server which needs to have ports forwarded, not both of you. I will assume that you're gonna host the game (=be a server). Follow your routers' guide and forward ports 63392 UDP and TCP aNd also port 29339 TCP. When forwarding a port, your router needs to know IP address of a computer where it has to forward the port to. You can find it if you do Start>Run>cmd>ipconfig. If your IP is assigned by a DHCP, it might be a problem. You can find that your from the ipconfig printout too.