Sorry I posted too soon. I forgot to mention that now the system is set to Router mode. It is no longer in AP mode.

@David-TP Yes, the way you depicted it was how I described it. That setup was unstable somehow with the main deco losing internet access. Now the setup has changed. Now it is bbox - main deco - zyxel...

I'll add some more details Internet enters on a bbox3v+ to which is connected the main deco a powerline adapter, tp-link 1Gbit, for tv, another powerline adapter, TL-WPA8635 with wifi disabled, which...

There is something strange going on with my network setup and I am wondering if any of you can help figure it out. There's currently 9 deco units, all m9 plus v2, in use. Set up in AP mode with some...