channel choose

I have an RT-BE92U router and, being quite isolated, 2.4Mhz works pretty well here, especially as our house is quite large. I'm confused by what Asus means by 'Control Channel' and 'Extension Channel'. All other routers I have ever used just have a plain Channel number. As I am using a TP-Link...

I have install GT-AXE11000_386.7_2 merlin firmware on my GT-AXE11000 and found that my device connected to 5G wifi has been fored to chosing 20Mhz stream which has been tested on 3 different device, max speed is 286Mbps, any setting change is not working. After i install the old version...