@Kevin_Z i have checked with every channel on both firmwares.After updating to latest mentioned firmware this problem occurs but on the previous firmware every channel on 5ghz works fine.

After updating to firmware Archer AX20(US)_V1.2_211231, 5Ghz or Wifi 6 is very unstable, Most of the time its not even in the list of scanned networks but everything is good in previous firmware.

@Kevin_Z In Vlc for android settings > advanced > prefer smb 1 after unchecking this option i can acces files without username and password Other than smb i don't see any other problem just this.

i noticed that in usb sharing when secured sharing is enabled , when client disables smb1 support i mean he uses smb2 or smb3 protocol to access usb shared files , he is not asked to enter username...