Hello!

A few months ago I bought a wifi extender since my house has 2 floors. I have a TP Link Router Archer C1900

while my wifi extender is a TP Link RE505X 

Firmware: 1.0.12 Build 20211107 Rel. 182157

Hardware: RE505X v1.0

I set up my wifi extender, followed the instructions and everything was fine. I downloaded the TP Link app and set up the wifi extender on the recommended location. All the lights from the wifi extender turned blue and it was working fine. However, when I went to my room, I had low signal and my internet turned slow and I couldn't stream movies or have good internet connection. So I decided to move my wifi extender to my room and all the lights turned blue EXCEPT for the wifi signal icon which was red. The app recommended me to move it to a better location, BUT I had good connection and fast internet. However from time to time, my wifi would go down and come back again. My house has concrete walls, so maybe it has something to do with it. 

So in short:

If I put the wifi extender in the recommended area, all lights turn blue, but I have a weak signal and the internet is slow.

If I put the wifi extender in my room, all lights turn blue except for the wifi icon and I have strong signal, but the internet goes down and then comes back.

Is there a way to find a good balance and have a good wifi connection despite my house having concrete walls?

Please let me know as soon as possible.

Thank you!