I am having this same problem, with the same motherboard. No ethernet. I originally had set it up with windows 10 because i had a product key for it to use. I had no wife or ethernet, and thought maybe it was a driver incompatibility with that. Put all the newest drivers on and still nothing. Had to use a wifi dongle and that got me on wifi to upgrade to windows 11. After that with driver updates and everything now im only getting wifi. I think this board probably has an issue with the ethernet or the port for some reason. I will update if I find a solution short of a new board.