David-TP wrote @Kengu Welcome to the community. Have you checked whether the 2nd Deco M5 works properly on the Ethenret Backhual over the Deco APP, such as: It is also suggested to replace the...

Hi, I have a somewhat different setup: WAN is connected to a router with it's wifi disabled. I have 3 Deco M5 configured in AP-mode 1st (primary) M5 is connected to router via ethernet (at the far...