We use a RUT955 Modem, which worked fine for a couple of days. Now the modem loses its data connection frequently. Therefore I introduced an automatic reboot rule, which restarts the mobile connection when the VPN service portal cannot be reached. This does not work at all.
After triggering a reboot via SMS, the modem works fine and connects to LTE without any problems.
I am sure that the signal quality is not the best at the application area. But I expected that the modem goes online again without any external help.