Connection issues with 2.4 ghz going through several walls

Linksys WRT1900ACS with OpenWrt 19.07.6.

Lately I noticed that on the 2.4 GHz wifi, once i go a couple of walls in my house (made of concrete), the connection completely dies even though my phone the wifi signal indicator is good. Yet in the same room with 5 GHz, there's no problem. I don't understand. I thought 5 GHz is suppose to have issues going through walls.

Also the bitrate for 2.4 Ghz is stuck at 72.2 Mbit/s and i've seen it drop as low as 20 Mbit/s

EDIT: After hours of troubleshooting. It turns out that the Hard Drive dock that I have plugged in the USB 3.0 interface is causing interference with 2.4 GHz. Switching back to Linksys firmware with the HDD dock plugged in also suffers the same issue. When I turned it off, the problem went away.

Then researching on this brought me to this


Yes, interference is a real radio problem in all frequencies!
I guess thats why USB3 cables so often are so thick because they have a screen inside.

And the 5GHz actually interferes with the weather radars...

You have thin concrete with small amount of steel in it I must say. Where I live if you go two concrete walls from the transmitter (all transmitters) all signals in all communications systems have dampened so much that nothing works.