Have you experimented with modemmanager/networkmanager to handle the configuration of the modem? For me that has worked quite reliably across a pretty large fleet of devices with a Quectel EG25 (qmi over usb).
Regarding FW updates, have you tried opening a support ticket with Quectel? For me they have been extremely responsive and helpful, providing extra documentation on special AT commands and stuff.
Regarding FW updates, have you tried opening a support ticket with Quectel? For me they have been extremely responsive and helpful, providing extra documentation on special AT commands and stuff.