@YanAndrew
When you have Satellite Decos connected wirelessly to Main Deco, their optimal location is not in rooms where you want best WiFi signal.
Taking Study room as an example. I am assuming you want very good WiFi signal there, so you placed Satellite Deco in that room, and you also have Main Deco on same floor. Like that:
[Study, Satellite Deco]<----------------------- X ------------------------->[Main Deco]
Where X is distance between Satellite Deco and Main Deco.
The optimal location for that Satellite Deco is in the middle between Study and Main Deco. Like that:
[Study]<----------X/2------------>[Satellite Deco]<-----------X/2-------------->[Main Deco]
Because Satellite Deco is connected wirelessly to Main Deco, all you need is electric outlet somewhere in the middle to try it.
-------------------------------
Same for the upper floor, where your bedrooms are. Do not place your Satellite Deco in bedroom, place it in the middle between Main Deco and bedrooms(s).
For example, my upper floor is all bedrooms connected with single corridor in the middle of the floor, from where stairs go to the ground floor. My second floor Satellite Deco sits in the corridor between bedrooms, and it provides coverage to all bedrooms. My ground floor Main Deco sits right under upper floor Satellite Deco, so that they are connected by strong wireless backhaul.
If you have larger house, you may need to figure different placement, but same principle applies: do not put Satellite Deco where you want to have best WiFi, put it between Main Deco and that place.
Finally, if you decide moving Satellite Decos to different places, check their Signal Source for backhaul signal quality. Example:
This Satellite Deco has good backhaul connection to Main Deco named Living Room. Not perfect, but good enough. It is placed correctly. Anything worse than that in signal level, or yellow/red signal leves, or just 2.4GHz but not 5GHz - means Satellite Deco is too far from Main Deco.