So for my guest house, I have a router connected to ethernet via PoE bridge. It's worked fine if a bit slow since I live in an area where only dsl is available.

Suddenly it stops working as it has one day.

Red internet connectivity indicator.

Does not work as a router for lan connections

Though it does still allow internet connection when in access point mode, though the indicator is still red.

I know very little about this sort of thing so I'm not sure where to start.

Skipping the router and going straight to the device works but I obviously need access for more than one.