RBE771 - Satellite distance for best performance

I've never trusted the values on those. What I usually use is directly connecting a laptop and speedtesting hardwired. That'll truly test that backhaul. 

when I first got into mesh systems (the original 50 series), I tested probably 20 locations in my home with different configurations of 1/2/3 satellites and then wired backhaul to determine the proper placement and amount of satellites. It makes a surprising amount of difference with a lateral move as sometimes things in the walls/floors cause interference. 

I'm 100% not saying you need to do that. But try a few locations and try with that wired connection so its only testing that backhaul. That's what I'd trust