I haven't commented on this discussion yet,
but this has completly to do with the NAT guide I have written to help you all out. If you didn't get it email wayne@igames.org and he will send you a copy.
Anyways during the ladder I have both centers host for a reason. The reason is that if one center has the ports wrong or closed and the other doesn't, when the host that is open correctly hosts then the other team can join.
If after the point where both centers have tried hosting and restarting their pcs it doesn't work then 90% or more of the time this means that both centers are configured incorrectly. I'm sorry to put it that way, but it's simple fact.
It all has to do with the computer being completly open, moderate, or strict.
Open can host all games (Centers like GameCafe for example), Moderate can only connect to centers with open or moderate connections (a great deal of centers maybe here), and Strict or closed can't connect to anyone but open.
I wish the game had an ingame testing tool like the XBOX 360 does. If you want to see what I mean hook up an XBOX 360 to your network and try getting it an open rating through the network troubleshooter. It is somewhat difficult to do, and with out multiple external ips you can only get open on 1 console.
Thus you can only host 100% of the time if you have open and you need more then one external ip if you want more then one computer able to host all matches. There are some other methods as well, but this one works all the time and isn't that hard to setup/
Chad "Mwarhead" Rippey
Events Admin - iGames.org
Manager - Gigabits LAN Center