I thought I’d leave this for posterity just in case someone else runs into this problem.
Bought a new Asus Prime Z270-A and after installing windows the Ethernet connection wasn’t showing up. This is problematic because no updates or anything can be applied until you get that ethernet running.
The Ethernet adapter was showing in the device manager as an “unknown device” and everytime I tried installing the drivers Windows couldn’t find the device. I tried installing from usb flash drives from DVD from my tethered phone… from everything I could think but it still wouldn’t work.
So here was the solution after reading this post
They only got the first part right
1.First boot into your BIOS setting, go to boot, then go to the area labeled CSM, and set “ignore” option in the "boot from network option."
2. Start Windows again and in the device Manager the unknown device is still showing instead of an internet connection.
3. Click on the unknown device and click uninstall. It should disappear from the Device Manager
4. Now reboot the computer and on reboot you should have your ethernet cable plugged in.
5. Windows will automatically load the driver on reboot and it should work.
Hope that helps anyone else who ran into this issue.