I have no idea about that device, but as i recently was tearing my hair out with the same issue: check your ports.
My device is using port 5013, and i had that open in the firewall, but only after opening 5013/UDP in addition to 5013/TCP, my tracker showed "GPRS:1".
So it's not that the device didn't have a GPRS connection, is just couldn't connect to my Traccar instance!
thank you very much @jangrewe, it was the port that was blocked
Any idea how to fix this?