My main Deco is connected to a switch and a second deco as well.

My third Deco was connected via WiFi and was working fine for more than 6 months.

But at a certained moment the third one stopped working.

I think it happened after an upgrade where the 3rd wasn't upgraded.

I resetted the 3rd one, put it in a new Network in the Deco app so I was able to manually upgrade this unit as well.

After the upgrade I resetted the config and added it back to my home network in the deco app while connected via Ethernet.

Everything was working fine again.

However if I want to switch the 3rd one from Ethernet to WiFi mesh it doesn't connect to the Main Deco.

I have tried to reboot all of them, downgraded all of them, moving them around the house, nothing helps.

Since I own a 4rd unit which I am not using for over a year, I added that one as well and it shows the same behavior.

For my understanding, do I need to manually change anything if I want mesh over WiFi?

By the way, I am using the Access-Point mode and my setup was working fine with a combination of ethernet and wifi mesh.