Thanks ... we had the same problem here.
Ethernet worked fine out of the box, ... switched to wifi, .... had some updates in auto mode ... wanted to go back to Ethernet (after final installation of the dock in the employee's office ... boom ... no Ethernet found.
Unplugged the dock from the power supply ... plugged it back in and problem solved.
Thanks
Unplugged the dock from the power supply ... plugged it back in and solved my problem too.