I'm also having the same problem with my game.
My friend and I both bought this game to play the online game. After many, many, many, many tries, we still are unable to join each other's games. We can both join public games but usually don't end up in the same game plus we don't really want to play with others...
There has to be a solution to this... Can Ubisoft really just drop the figurative ball and do nothing? I doubt I will be purchasing anymore Ubisoft games, if that's the case.