I seem to be among many others who are experiencing the same problem.  I bought your Sins of a Solar Empire game yesterday with plans to not only enjoy the singleplayer game but to engage in epic battles with my son who lives in another state and also recently purchased the game.  When either he or I attempt to create a game, we get the message that our firewall or router is blocking others from joining our game.  I enabled my firewall to allow the game thorough, and the same problem exists. I diable the firewall entirely, same results.  I bypass my router and STILL get the same annoying message.  I WAS able to join someone elses game but not my son's, and after an hour and a half I surrendered to single player mode.  ALL of my entire library of on line multiplayer games work as they should.  I have windows Vista and my son has Windows XP.  Others in the game lobby also could not join a game I created.

PLEASE tell me that Ironclad or Stardock or SOMEBODY plans to fix this highly annoying issue in an upcoming patch (hopefully SOON).  I feel that I have wasted my money on a broken game.