I just set up my AXE300, and the second 5GHz band, the one with the higher channel numbers, is totally useless. Most of the time, it doesn't even show in the list of available networks(and the devices I'm trying to connect are less than 15 feet away with no walls or other significant barriers in  between). When it does show, devices are unable to connect to it. Those same devices have no problem connecting to the lower-channel 5GHz band, and the ones that are capable are able to connect to the 6GHz band(though not with WPA3, I have to use Enhanced Open or they can't maintain the connection, this is with Intel AX210 network cards). 

Why is the second 5GHz radio completely useless? If I reboot the router it will show in the available networks list for a lttle while, but I won't be able to connect and it will eventually vanish.