Okay so my family pays for a 100mbps connection speed and we usually get about 90mbps on speed test. The problem we are having is that the second my dad turns on his computer, the connection speed drops to 10mbps. I tried running net balancer to see if he had something using up the bandwidth but everything seemed normal. We thought it was the router so he switched his cable to a different port and that seemed to fix it but a few days later the problem came back.

I have no clue why his computer is slowing down the network so severely and I'm hoping someone might have an idea.