What can I do to make my sons xbox stop lagging I have a router hooked to my home computer and when I am on the computer and he is on his xbox it makes him lag any suggestions

Your problem is in your question. With the router hooked up to the computer its using the Internet from the router which is probably what your son is using as his Internet source causing him to lag. Just make a schedule. Time him then have your time on your computer then when your done he can get back on his Xbox.