Nefit Easy dropping from 2.4GHz ...

Hi,

I have a strange issue with my Nefit Easy thermostat, it drops of my 2.4GHz and has lots of problems reconnecting …

running 3x hAP AC (RB962) with ROS-6.45.3 .
2.4GHz and 5GHz both running same SSID
gateway to ISP is a CCR1009 on 6.45.3

about 20 different clients without problems (iPhone’s/iPad’s/MacBooks/W10 clients/Samsung TV/Android phones/etc)

It is just the Nefit Easy that has problems,
sometimes it is connected for 40minutes, sometimes less than 5,
sometimes it reconnects in 5 minutes, sometimes it takes hours !

People in the Nefit community told me that the Nefit Easy has problems with dual-band wifi running both the same SSID, strange because the Nefit Easy does not have 5GHz
They told me to disable band-steering but ROS does not has that ..

So now the question, how to debug this behavior ? How to fix ?
People with other vendor hardware do not have this problems …

Regards,
Eddie