Log into the router's control panel.
Most of them have an option to set IP based rules.
You can set up a rule that only allows your son access to the Internet at predetermined times. You may also find that you can set a rule that limits the bandwidth that he's allowed.
If he's giving you that much trouble then I would simply withdraw his Internet
privileges for a certain period of time - after all, he's the child and you're the parent, sometimes kids need to realise that their negative actions have negative consequences
