Open the Settings app
Tap Wi-Fi
Tap the connected Wi-Fi network name
Check the router details or network information if shown
If the GHz is not shown, use your router’s app or admin page to see whether the network is 2.4 GHz or 5 GHz
If your Wi-Fi network names are different for each band, connect to the one labeled 2.4G or 5G
If needed, use a Wi-Fi analyzer app or check the router label/manual for band information