Hi
Thank you for your response, what is you firmware version?
Kindly try to update the FMC650 firmware to the latest from the firmware errata of FMC650 there is a lot of improvement in the device network operation.
Download link: https://wiki.teltonika-gps.com/view/Special:Redirect/file/FMX65.Ver.03.00.15.Rev.13_and_configurator.zip
Best Regards
Maynard C