I just bought the Cerbo GX and GX LTE 4G-A modem. The Cerbo does not recognise that the modem is connected ("No GSM modem connected" in the GSM page) but the modem itself changes behaviour depending on whether the USB plug is connected to the Cerbo or not. There are no lights at all if only the 12V power is connected, but when USB is connected then I get a slow flashing blue light ("Network available").
I have tried all three USB sockets on the Cerbo (including the 'power only' one intended for the touch screen) with the same results.
Not very impressed with the Cerbo so far - this unit also cannot talk over BT (separate issue created for that)