Looking over the logs again, most of the devices show FTP authentication errors. This looks like an incoming connection to the device. This is filling up the logs and makes it difficult to diagnose other issues. it could be causing the issue or at least be making it harder to spot. Again, I recommend updating the firmware to the latest to ensure the firmware is not causing you issues. To help rule out issue with the modem please also run our SIB fix tool to ensure your modems are updated too. More info is found here with a link to download the tool in section 4.1.
Please be aware this support forum is run by a team in the united states. We might not be aware of an issue specific to your region. I would recommend reaching out to your distributor they should be able to assist you and get in touch with your local support team. They might have further suggestions.