In order to resolve the issue that you are currently experiencing, additional provision of further confidential details is required. Hence, it is recommended that you reach out to your designated sales manager or the reseller from whom you acquired the device in question. They will be able to assist you in addressing this matter more effectively.
There are also some improvements to mobile MBN selection in 07.04.5, so make sure to update to this firmware, and make sure the PAP username and password are correct.
Since the contents of the old support forum are lost, I will ask you to navigate to System → Administration → Troubleshoot, press the Show button on the System log, and after replicating the issue with APN cda.vodafone.de copy the logs and paste them in the next message. Make sure to censor sensitive information like PAP authentication arguments, IP addresses, etc.
It seems like the issue is with the APN authentication, as the device is registered to the operator (not sure how their tech did not see it, perhaps they are checking mobile data status?).
From the logs it seems like the APN used is cda. vodafone. de (with spaces), was this added when pasting here due to forum restrictions? Or perhaps it was entered incorrectly?
Since further troubleshooting would require setting up a remote session, I’m afraid there is not much that I can do here, since this forum is public. I would recommend you to reach out to your designated sales manager, reseller, or if both of those are not an option, fill out the Contact Us form here: Teltonika Networks - LTE Routers, Gateways & Modems for IoT
When reaching out, make sure to link this forum post for reference.