I presume Phex has apples NAT-PM support because it's not totally identical to UPnP. But I'd give it a 98% chance it is supported.

Have you been able to connect via your BSU wireless internet with other p2p programs?
By wireless do you mean you connect to your ISP via a wireless connection & not via cable/phoneline etc. I am aware some such services have their own firewalls at their own base. Also a question of your receiver, whether it has a nat or similar internal firewall.
Any specifications of other equipment you are using?

BTW which port are you connecting through for Phex?
Try this test with your browser: Port 6346 test The page should say 'Your test worked!'. What happens when you go there?