Drift 868Mhz ,temperature

For several days in France it has been very hot and we have observed that many lora RAK3271 modules no longer communicate with the gateways. We observed with the spectrum analyzer shifts at room temperature of the frequencies 868.100 Mhz, 868.300 Mhz and 868.500 Mhz, we note 868.07 Mhz, 868.270 Mhz, 868.470 Mhz. We do not understand why at room temperature these frequencies are already shifted but it remains functional. Exposed all day to temperatures >40°C, the modules transmit but with an even more offset frequency and the transmissions are no longer heard by the gateways because too much frequency offset, they are visible on the spectrum analyzer.
What should be done? Is a calibration possible?

Hi @d.hinault ,

This is an internal test report for the temperature drift of RAK3172.

I am not sure why you get higher drift. Maybe you can share the hardware setup you have and the software you use to test.