Disabling internet

Long story here, bear with me... I have a teenager who likes to use internet past 9pm, which my wife and I do not like. Every single night, I have to tell him - you have xx minutes left. He gets all pissy, but hey, that's life. Instead of going through that crap every single day, I would like our entire internet to be shut off - on all 3 computers - AUTOMATICALLY, at 9pm. So he knows at 9pm, the internet gets shut off. My router doesn't support time frames. It does support shutting off individual computers, but I would have to do this manually. I don't want to have to do it. Is there lan software that I can run on one computer, to shut off internet in the whole house? Even if its a screen capture mouse-movement program like snag-it that automatically selects the options to shut off the internet at a given time. I don't know if Snag-it has an automated feature where it plays-back your recorded macro at a certain time. I don't mind leaving one computer on for all this to happen. I know, "take control of your kid". Well, we do, I just don't want to have to go through the "aww... can I have 10 more minutes" every night. If its an automated macro program, that will be awesome. If it shuts off the internet for everyone, that's also great. Thanks!