Why am I always instantly disconnected from XBOX live after signing in?

I keep getting disconnected fro xbox live. this has been a problem since I first got xbox live, it takes 30 minutes or something like that and then its disconnects me, for example if im playing call of duty multiplayer it will take me out of the the game. I have a xbox router thingy that is plugged into the back of my xbox and wireless box thing. could I have a easy simple question to get rid of this problem thank you I keep getting disconnected fro xbox live. this has been a problem since I first got xbox live, it takes 30 minutes or something like that and then its disconnects me, for example if im playing call of duty multiplayer it will take me out of the the game. I have a xbox router thingy that is plugged into the back of my xbox and wireless box thing. could I have a easy simple question to get rid of this problem thank you