@metalmatt 

Hi,

It all depends on for which country or region your Archer AX72pro is made for.
You can find that information by looking at the sticker on the underside of the router's housing.
The most common ones would be "Archer AX72pro (EU)" and "Archer AX72pro (US)", but there are others as well.

In case your AX72pro is the European (EU) version, then channels above 140 are not supported. Maximum permitted transmit power for channels 36 to 64 is 200 mW, while up to  1W (1000 mW) is permitted for channels 100 to 140. But remember that especially client devices often do not transmit at the maximum permitted power levels, so you might not actually notice a difference in range.

As mentioned above, it may be all different if your AX72pro is made for another country or region.

  @woozle 

Thanks for your help :)

  @woozle 

I have just tried to switch channel from 44 to 64 as a test but it does not work, puts it back to 44, even though the option is there to change it up to channel 128.

Please ignore this. It worked :)