One of the joys of using Windows is when things that have been working forever mysteriously quit working. That was the case with my Dell XPS 15 laptop running Windows 10. "All of the sudden" the wired ethernet port on the docking station quit working. There was probably/possibly a Dell/Windows update in the interim that broke it but who knows. It took me a while to figure out, but to solve the problem I used these instructions for manually fixing the docking station drivers from the dell website (expand the "Installing drivers" node). I skipped some of the steps, but I updated the bios and thunderbolt controller driver from this link. I updated the docking station firmware from this link. At this point I received a message that a new thunderbolt device was detected which made me happy.
I downloaded the realtek USB GBE ethernet controller driver from the drivers page for the laptop, and first used it to remove the existing installation and then ran it again to reinstall. At this point, I turned off the wireless and confirmed that the wired ethernet port was indeed working correctly.