RT AX88u pro | 2.4GHz Band Disconnecting Clients Until the Network Fails

[zuzuzu]

I experienced the same issue with an AX82U router and replaced it (after consulting with ASUS) with an AX88U Pro, but the problem persists.
Typically, one client keeps disconnecting and reconnecting every few seconds until the entire 2.4GHz band fails.
When I disconnected the problematic client from the network, the issue started happening with another client.
Seems it's likely an issue with the Asus router itself.
I've come across many posts reporting the same problem, but there doesn't seem to be a definitive solution.
I've tried almost everything: adjusting every possible setting, moving the client to a separate IoT network, but nothing has worked.
The 5Ghz network works fine.

Frustrating :|

 

[bennor]

It may help provide context if you include your RT-AX88U Pro firmware version. Your Wireless settings, the WiFi client that is having the issue and if you are using a Guest Network (or Guest Network Pro).

 

[zuzuzu]

Firmware Version:3.0.0.6.102_33340
The clients are different, it's a boiler smart switch and once I disconnected it I got the same behaviour for my robot vacuum (dreame x40 ultra), i didn't try to disconnect both to see if it goes on.

Guest Network Pro.

For the settings I tried various different settings, today I changed the Channel bandwidth to 20Mhz to see if it helps