Using the Chateau 5G AX router, which apparently features the Quectel RG502Q-EU module**, in conjunction with SIM cards in the network of O2 Germany (MCC 262, MNC 7), the registration on their network takes way longer (30-40 seconds) than on Deutsche Telekom (few seconds).
Since O2 unfortunately disconnects the session about every 24 hours, this causes an outage of often half an hour or even longer as the Mikrotik at first fails to reconnect. While this can be somewhat circumvented by having the connection reconnected every 24h on the router side with a script, still those 40 seconds of being offline remain.
Interestingly, other routers (re)connect on O2 a lot faster (ZTE MC801A about 12 seconds and the Acer Predator a few seconds only as well).
As both, the Mikrotik with Telekom and the orhers with O2, are quick, I assume some issue between Mikrotik/Quectel when being used with O2.
Installed firmware is RG502QEAAAR13A02M4G and I’ve already described the issue in their forum.
** since there is hardly any information available about this, the side question arises: I always read that Quectel provides “modules”, mainly for IoT applications and that module x and y would be based on Qualcomm’s Snapdragon, what exactly is the difference then between a Quectel module based on that and a “plain” SDX55 chipset which routers such as the ZTE MC801A or many phones use?