Hi again,
I live in eastern Europe (Macedonia) and before the downgrade on the latest version 2.10.46 the router was also set to "Auto" selecting the channel and that channel was 36.
After the downgrade I had restored/uploaded the saved settings before of the flashing the router and what I have noticed is that now the channel is 149.
No, I can choose every channel listed but when I set to Auto, then it's connected to 149 which is not listed. I am using this Auto setting because there no other 5G network around my home.
This is Xiaomi Router 3 and I don't know how familiar are you with this routers, but stock/fabric software is really a crap. Every user is having some issues and didn't believe that I had fixed my 2,4ghz network with downgrading the firmware to 2.10.42.
I have two of them.
One is Xiaomi Router 3 with stock/fabric firmware.
Second is Xiaomi Router 3G with Padavan firmware.
Both of them are not on the same network.
However, on Dell's support page it is true as you mention that they are using one driver software for different WiFi cards from Intel.
I had also tried to install the driver directly from Intel support page. ->
Downloads for Intel(R) Dual Band Wireless-AC 3165
That does not fixed the issue with bad signal on 5G network.