I think channel 11 is the default as it is the highest frequency band and has a slightly shorter range signal but higher speeds. It’s one of three default channels (1,6,11) that don’t overlap each other and so don’t interfere with each other, much. Of course if you are in a shared house etc you will get many uses of the same channel maybe from separate routers even.
https://www.metageek.com/training/resources/why-channels-1-6-11.html
However the problem with is that bluetooth uses that range, too ( 2.400 to 2.484GHz) so if both are enabled channel hopping can occur and loss of packets may occur, loss of call even) So unless you want to use bluetooth disable it in case the network is 4G and you get interference. Bluetooth and 5G are fine, but who has 5G ~ not me.
Off course bluetooth and 3G are fine
In the UK the new 5G mobile is between the two around 3to4GHz