RAK3172 500kHz join behaviour

I am trying to understand the RAK3172 (firmware version 4.0.2) join proceedure on band US915 specifically with regards to attempting 500kHz channels.
According to the “RP2-1.0.3 LoRaWAN® Regional Parameters” document:
“For rapid network acquisition in mixed gateway channel plan environments, the device SHOULD follow a random channel selection sequence which efficiently probes the octet groups of eight 125 kHz channels followed by probing one 500 kHz channel each pass.”

Is this how the join proceedure works or does the RAK3172 have to be explictly set to DR4 for the 500kHz channels to be attempted.

Hello Marina,

The DR that is set with AT+DR command or with API call is not used during the join process. Instead the device follows the specification and tries 8 times to join on a 125kHz channel and then on a 500kHz channel, independent of the data rate setting:

Thank you for your reply. What version of the firmware did you use for the example above?

Hi Marina,

I used the latest RUI3 version V4.0.6