RN2483 433MHz problems

I would expect you need to pause LoRaWAN (mac pause) to issue radio commands (data sheet 2.4.6). To set the frequency for LoRaWAN you should probably use mac set ch commands. Also, which version of the firmware are you using as Appendix A of the data sheet mentions changes have been made to the 433 MHz band in release 1.0.0 of the firmware.