We have written about the Quectel RM520N-GL 5G cellular modem before. Back then it was about setting up the software to establish a functioning Internet connection under Linux.

Now there is another article about the modem - but not because everything worked as intended straight away. Rather, this time we want to give you an insight into our daily struggle with and against technology. Because not everything that should work actually works in the end. Even if - as in this case - the electronics have already been used successfully in one way or another.

On our odyssey in search of a 5G cellular modem, we have tried several modems from different manufacturers. Unfortunately, the commissioning was not always successful. Sometimes the driver support in the Linux kernel was completely missing - sometimes the control via NetworkManager / ModemManager was buggy or not possible at all.

Easy commissioning and stable operation are important to us. Since we do not want to use the modems on only a few devices, a manual adaptation of the Linux kernel is usually out of the question for us. The effort involved is too great and the consequences for the further life cycle of a product are too unclear. Therefore, the operating system - often a Raspberry Pi OS - should be used in its factory state and without major adjustments, if possible.

Two modems have emerged for us that work “out of the box” in combination with the current Raspberry Pi OS on Debian 11 “Bullseye” basis (kernel 6.1):