Router RT-AX58U can't connect some devices via WIFI

[DeZe]

I have a RT-AX58U with several devices connected to it. Sometime last week the TV, the IKEA smart hub and my raspberry started having problems. The TV couldn't connect, can't even find the ssid, and the smart hub didn't connect to the lights.

Everything could connect before and I didn't change any settings before it stopped working. Laptops and phones still work without a problem

I restarted the router, didn't help. I did a factory reset and it helped for some time, then they disconnected again.

I disabled WiFI 6, that also helped for a bit -- I could find and connect the wifi on the TV, but then it stopped working again. 

One thing that I've noticed is that when I move around, or do stuff with devices connected to the ethernet, it seems to brake. For example I restarted the smart hub and I think it was then the TV disconnected from the WiFi the last time.

Firmware is: 3.0.0.4.388_25210-gfbda585
It is the latest, I don't know if I can see when it updated.

[Saltgrass]

Some of the recent router updates have added additional security as far as which WPA version they require.  If you have an older system using WPA or even WPA2, it might cause problems for your network.

If this might be a possibility, you might try turning off one system, at a time, to see if it is involved.  I had an older printer that was causing other devices to disconnect from my network.

[jzchen]

Zigbee, Bluetooth, and 2.4 GHz WiFi overlap frequencies and can interfere.  You noted you were rearranging Ethernet connections?  Did you move the IKEA hub or other close to the router?