As of today we have two access points installed, where I copied network name and password from our old WiFi router for the sake of easiness.

That is what I thought, because of a smart TV , a chromecast 4K, a Roomba 675 etc etc etc.

Now that little vacuum cleaner is giving me some headaches. It "runs" on 2.4Ghz, as the only older device in this place. And to communicate with it, on the old wifi we had 3 different networks. Clearly named 5ghz, 2.4ghz and guest. We could communicate with our phones via the 5ghz network and the router would talk 2.4ghz with the Roomba.

Now the new Deco M9 Plus operates on those two bands with one network name. And that caused some trouble because I had to tell my Roomba to start talking to a differently named network. So disconnected the new Deco set-up, plugged in old Wifi and changed the name of my 2.4ghz network to be called the 5ghz network. So that name/password settings would be stored in Roomba correctly. So after name change and succesfull set-up of Roomba I unplugged old system. Fired up the M9 and Roomba connected to it. yeey!

But somehow this doesn't seem to work at the moment with this new system. I cannot change my iPhone's connection type to 2.4 manually? So I can't talk to my Roomba while my phone is on 5ghz. Does the system actively block devices on different bands to talk to each other? What can I do to fix this?