Ethernet backhaul on Deco M90 Plus not working
I've set up 3 Deco M90 Plus around my house in router operation mode. The main Deco is wired to my telecom modem (which is in bridge mode), while the other Decos are using wireless backhaul. Everything works nicely, though I want to use ethernet backhaul on the Deco on my 2nd floor because an ethernet cable is nearby available and wifi source signal is a bit poor there.
When I plug the ethernet cable in nothing happens... the signal source is still showing the wifi signal of the main deco on the first floor, it's not showing the ethernet symbol. I tried using a different ethernet port on the Deco and a different ethernet cable doesn't help either. There is no switch in my entire configuration either.
Does anyone have an idea what might be wrong in my configuration and what can solve this making the ethernet backhaul work? Thanks!