How to perform a fast connect ?

Below is an example of a way to use our CZ (fast connect command) to implement your desire to control connection to either 2.4 GHz or 5 GHz.
To make the ISM43340 module connect to a 2.4 GHZ or a 5 GHz access point with the same SSID, use this Fast Connect Command (‘CZ’).

Firmware release C6.2.1.8 or newer.

‘CZ’ command (Fast Connect)
Usage: CZ= or
band: 0=5GHz, 1=2.4Ghz
channel: 1-14, 36-165
bssid: xx:xx:xx:xx:xx:xx
When enabled the 1st connect scans for the SSID and gets the additional data to speed up subsequent connections.
Note: data is not stored in non-volatile memory, must re-issued if module is reset or power cycled.

In this case we are manually setting parameters.
Example:
> C1=ism_demo //SSID name
OK
> CZ=1 //Enable Fast Connect
OK
> F0 //Removed unrelated access points for all scans
#001,””,4C:01:43:62:1A:D9,-86,300.0,Infrastructure,Open,2.4GHz,1
#010,”ism_demo”,20:AA:4B:93:84:8B,-37,144.4,Infrastructure,WPA2 Mixed,2.4GHz,11
#014,”ism_demo”,20:AA:4B:93:84:8C,-51,144.4,Infrastructure,WPA2 Mixed,5GHz,165
OK
> CZ=1,11, 20:AA:4B:93:84:8B //Setup for 2.4 GHz
OK
> C0
[JOIN ] ism_demo,10.109.70.136,0,0
OK
> F0 //Scan starts with the current connected channel
#001,”ism_demo”,20:AA:4B:93:84:8B,-41,144.4,Infrastructure,WPA2 Mixed,2.4GHz,11
#013,”ism_demo”,20:AA:4B:93:84:8C,-50,144.4,Infrastructure,WPA2 Mixed,5GHz,165
OK
> CD
OK
> CZ=0,165, 20:AA:4B:93:84:8C //Setup for 5 GHz
OK
> C0
[JOIN ] ism_demo,10.109.70.136,0,0
OK
> F0 // Scan starts with the current connected channel
#001,”ism_demo”,20:AA:4B:93:84:8C,-47,144.4,Infrastructure,WPA2 Mixed,5GHz,165
#019,”ism_demo”,20:AA:4B:93:84:8B,-39,144.4,Infrastructure,WPA2 Mixed,2.4GHz,11
OK
> CD
OK
> F0
#001,””,4C:01:43:62:1A:D9,-86,300.0,Infrastructure,Open,2.4GHz,1
#018,”ism_demo”,20:AA:4B:93:84:8B,-38,144.4,Infrastructure,WPA2 Mixed,2.4GHz,11
#024,”ism_demo”,20:AA:4B:93:84:8C,-51,144.4,Infrastructure,WPA2 Mixed,5GHz,165
OK
>