Apple:

If the Ethernet connection on your Mac stopped working recently, check System Information to find out which version of “Incompatible Kernel Extension Configuration Data” is installed. If you have version 3.28.1, you need an update. If you can connect to WiFi, your Mac will update to version 3.28.2 automatically, or you can follow the steps below to restore it manually.

It’s a relatively easy thing to check to ensure compatibility and, if not, to fix.