6ghz - won't turn off permanently - causing connection issues with many devices

Hi,

Is there a way to permanently disabled 6ghz?

I have several devices (PC laptop and iMac) that automatically choose 6ghz - but have really poor connection which causes major problems when working. 

If I disable 6ghz in the admin portal - then forget the network and rejoin the wifi on these devices - everything is fine and full strong connection. I also have 2 pods in the house.

This is a major issue as my wife really struggles with technology and when she is working can't afford for the router to turn 6ghz back on!....why is it doing this if I have disabled it?

Any help would be appreciated?

I tried to change the SSID name to separate 6ghz from 2.4 and 5ghz however you can't as it is greyed out

So frustrating