Netgear router c3000 model/ethernet ports not working

Please help me. I just got a brand new ethernet cord for my xbox one so I can play on wired connection. I go into my parents room and use a 10 foot cord and it works. My brother has a 100 foot cord going to his room and the internet works fine. I got a 100 foot Ethernet cord and ran it throughout the house and it will not work. If I plug my cord into the ethernet port my brother uses, it works. So I think it has to be the port. I don't know how to fix this or if I just have to get a new router. Netgear model c3000 has 2 ports so it should be able to run 2 ethernet cables.