I have 3 M4R Deco`s connected in router mode.

The main deco is connected thru a switch to my zyxel router with a cable

The two other deco`s connect with wifi to the main deco.

The one upstairs has very low signal strength due to concrete floors etc,(40mb/s The others have 380MB/s)

I also have a Lan cable upstairs with a switch connecting several users(pc,playstation etc) to my zyxel router,my question now is;can i connect the upstairs M4r with a cable to my switch and have better wifi strength?

I have tried this offcourse but the M4r goes red and doesn`t seem to connect to the network,even after a reset.

I also have tried to setup the main deco as a accespoint but that doesn`t seem to work either.

Any advice on how to fix this?