Xbox Live Dissconnection

I have frequently been having problems with my xbox live connection every time i log on and play for awhile it disconnects i've tried it on 2 different games and I've tested my connection but it always ends disconnecting in the middle of a game.

I have to computers one wireless one not but, even if there both off and disconnected from my modem xbox live tends to disconnect.

I would love help on how to fix this problem.

I just wanna play for longer than 30 min.