Model: https://www.tp-link.com/ph/home-networking/wifi-router/archer-ax72/

RE 215 AC750 Mesh Wi-Fi Range Extender, 7 pieces: https://www.tp-link.com/ph/home-networking/range-extender/re215/

Since day one I got issues with the 2.4 GHz band of this router, many smart devices just randomly lose connection. If i try to connect with my phone it goes from

"incorrect password"

to

"Unable to join, network is operating on Wi-Fi channels in use by several other nearby networks. Restarting your wireless router may allow it to automatically choose the best channel to use, and may resolve this problem."

Please note that I don't have any neighbors and no nearby networks in the area.

Firmware is up to date of router and all extenders, did several factory resets of all devices. Recently, I have changed the channel of the 2.4 ghz network to channel 11. Slight improvement, but still not reliable.

I tried to create a IoT network for the smart devices, but some refuse to connect to that one.

Anyone can help please?