And this is a good thing. There are a few things you can do to deter his addictive internet habits, and at the same time you will be helping him modify his behavior.
Frustration is the key word.
The magic of screen savers. They serve for more than one purpose. Go to your screen savers and set the timing for the screen saver to go on every 5 minutes. He suddenly gets disconnected every 5 minutes. He will then investigate the problem.