So here's the short version. We fiddled around with our router (a Linksys BEFSR41) and are able to join each other's LIVE games and play. However, last night we both tried to join my buddies Borderlands game, and only one of us could be in the lobby room at a time, and he couldn't join when we hosted. I have set up port triggering and enabled UPnP. It is an older router so could that be the problem or does he have to adjust his NAT on his end to join our game?