Hello All,
I can't figure out if this is a Sony TV issue or an Android TV issue. I have my 2015 Sony XBR directly connected to a Ubiquiti Edgerouter ER-X. I've noticed that when my TV is turned off and in standby mode, it's ethernet connection is constantly flapping from a connected state to disconnected and back to connected. Is this expected? I can't figure out why it would be doing this.
It's probably turning on intermittently to check for incoming requests while not taking up as much power. I had to set my Sony TV to not turn off WiFi so it will be able to turn on with Google Assistant commands.
Go into your router logs and check to see what's happening. I don't have the same router, so I can't tell you how to do it.