I have a Dual Ethernet Airport and I can connect to Battle.net just fine. That said I cannot vouch for the Airport Extreme. One thing to note is that battle.net does not like multiple clients from one ip, so if you are using your airport as a router for multiple computers and you are trying to have more than one user connect to battle.net you may have issues. It seems that the battle.net servers have trouble reciving multiple cd-keys from one ip and they get confused.