I have a question regarding network connections between different countries. To give this question some context, my brother recently moved to Denmark, and I still live in Canada. He likes to play Modern Warfare 3 with me, but we have issues joining each other's parties (we haven't successfully joined each other's lobbies yet). As in we receive the message: "Unable to join game session". Now is this because of one or both of our NAT settings, or is there a common issue with Xbox Live servers having difficulty connecting players who live far geographic distances from each other?

I occasionally have issues when playing MW2 specs ops with my gal chum in Wisconsin, but usually shutting the router down for a few minutes resets things and works okay.