Anytime I tried to join a Dominion 4v4, player v player match, I would get to the beginning of the game and get the boot. Then when I tried to go versus bots I would get another error message. Shame on me for not annotating the error message but hopefully other folks did. My NAT was green the entire time. I had to go to the Xbox Main Menu and Quit the game to reset it before I was able to play again. I tired this 4 times before I gave up trying to go player v player. I did this for Brawl as well.
I still enjoy the game and appreciate the opportunity for feedback.