Today I added a 4th Deco M9 plus (2nd hand) to my existing network. Installation succedes and the light turns green. I can see the new unit in my app overview, but it does not connect to any devices nor the existing Decos (also does not receive an IP). App says the device is fine, but it obviously doesn't do anything. Update, reset of the unit and reset of the network don't change anything.

Anyone experience with this situation?

Thanks in advance