Yes. I was also helped by a friend who is in the IT field. Otherwise I would never have noticed. I would not have thought of such a thing, considering that the devices are of a relatively new...

@terziyski Solved. I had to disable fast roaming, respectively the IEEE 802.11r function. It seems that some devices, such as these air conditioners, do not know this protocol. Thanks for the advice...

The only acces to the Deco is the Deco app, where i can't see o which chanel the Deco is working.

@terziyski Thank you for your prompt answer. How do i see on which wireless channel the connection was established?

Hello, I have the request to support me in a problem. I cannot connect the Hitachi Air Home 400 air conditioners to the mesh network created with Deco M4. I set Deco exactly as the device manual asks...