To preface, I am very very new at installing mods for Civ IV, so go ahead and assume that I have missed something extremely obvious to everyone else. I got Rise of Mankind 2.91 and A New Dawn 1.73 patch J about a week ago. I got it to play well in single player, both my brother and I got a feel for it. Then we went to play a multiplayer game, LAN as well as IP connection. Both of us have the exact same components installed and both of us can play single player. However, neither of us can see the other's hosted game in LAN, or the IP connection fails. Both firewalls are off. My computer is running Vista, his is running XP.