Some people say it's a problem with Belkin routers, or with UPnP & media server. Neither one of us have Belkin routers and both of us have disabled UPnP & media server on our consoles.
My next step is opening up ports. That thread was made back in September & I'm surprised Blizzard hasn't done anything to fix this problem. I never had any issue with XBox Live and now suddenly I can't join a friend's game on PSN.
Constructive help is appreciated; I'm not into console bashing & I understand things happen, I just want to get it fixed. Thx in advance.