Ok. My brother and I have 2 seperate xbox's and 2 seperate Modern Warfare 3's.
We play on the same connection.
When we both try to join each others game or just search for a game, we will lag out and it will usually go to a server is down pop up.
It never did this for any other game.
We played MW2 like this.
Is it a thing where we are playing on the same ip?
IDK i researched and it might be our router. It is a router modem combination...
It jus messes up on MW3