Hello and thanks in advance for the answer.

I live in a 4 floors house.

I bought a set of 4 decos (3 M4R and 1 E4)

I placed it one per floor.

Main Deco M4R in ground floor 

Satellite 1 M4R in floor -1 

Satellite 2 M4R in floor 1 

Satellite 3 E4 in floor 2

all of them have power strenght "medium"

Satellite 3 is connected to satellite 2 which is connected to main deco. Satellite 1 connected to main deco.

My ISP provider runs at 1gbps

If i connect to the wifi of the ISP modem, i get 800mbps

If I connect to DECO wifi on main deco, i get 250mpbs

Then, satellite 2 90mbps, and satellite 3 20mpbs

I set DECO network in accesspoint mode.

Can't find better positions to get stronger signal, i tried all combinantions...

But it seems that speed is cut of is already in Main Deco, non only in the satellites (which I would explain with distance, even if it's just one floor away).

Is there any chance to avoid this speed drop? 

Thanks in advance!