Good morning @asorho ,
You can navigate to the FMB140’s firmware downloads, and then you’ll have to flash the device with the new firmware.
The version 04.00.00.Rev.01, released January 2025, is the first one to support MQTT and Codec JSON, so any version since that one should be good for you.
Teltonika has better guides about flashing devices than I do, so I suggest you look into their documentation,
Best of luck!