Hard wired windows 8.1 computer can't connect to internet through r6900 router- advice appreciated

It turns out that the problem was hardware related after all. After I replaced the modem and router, AND bypassed the currently installed ethernet port with a usb-ethernet adapted I was able to get back on the internet using the ethernet connection. Thank you all so much for your help!!! The driver update suggestion got me thinking about the ethernet port which lead me to try and bypass the existing port which solved the problem. I definitely appreciate the suggestion! This problem lead me to upgrade my network hardware (router/modem) and scan all of my computers for viruses (some found and removed) so it all turned out well in the end. Thank you!