So we have couple of AndroidTV in our house, both does that.
Tested using FAST test:
Ethernet: tops at 9-15Mbit. Movies and shows can't get to 2160p or 1440p unlike wifi.
Wifi: 50-60Mbit.
Ethernet real speed (Tested with speedtest): 100Mbit.
All other apps runs just fine on Ethernet, anyone having this issue too?
This sounds more like an issue with the ethernet cable or your network configuration than Netflix changing servers.
For Netlfix to change servers I can only think of a VPN or a different routing table configured in your network.
How is your network in your home? Where is the wifi connecting to and where is the ethernet connecting to?