Try booting into a live image of a debian distro (pick any one you want that can boot into a live image), then try the Ethernet port. Is it working? If not, either your bios shut it off or the port is broken. Several years ago, I had a broken wifi adaptor that happened to break at the exact same time as (or super close thereto) me installing GIMP. No way GIMP caused it. If the port does work on the live image, then it’s likely a driver issue with your install. Try it and let us know the results.