Constant wi-fi drops by mobile devices with 6ghz gateway

With such limited range on 6ghz, we have numerous dead spots throughout the house. We got the wifi pro extender, but it does not seem to do anything to extend the 6ghz. A technician even suggested where to put it, but the dead spots remain. The other main problem is, our phones and tablets will lose the 6ghz, but instead of just switching to 5 (or even 2.4), the phones completely disconnect from wi-fi and switch to cellular. Obviously this causes a lot of extra cellular data in our house, where we pay  for wi-fi service. 

Our house is not big, yet all this new 6ghz technology does not stretch ANYWHERE. Are we just supposed to pay for a bunch of extenders/mesh devices to actually make it work? When 7 comes out, do we have to be sitting on top of the router to get a signal? 

I've fiddled with all kinds of settings on Intelligent Wifi on our Samsung phones to no avail.

If anyone has any suggestions on how to 
A) Get the 6ghz signal to actually reach everywhere 

B) Get the mobile devices to never drop the wifi, but just switch to 5 or 2.4 if when the 6 signal gets weak.

Thanks!