ER7406 - Telekom Germany SIP registrations randomly fail (401 Unauthorized)
I am observing an issue with an ER7406 (v1.0, FW 1.3.2) related to SIP registrations of a telephone system and would appreciate your assistance.
The setup consists of an Auerswald COMtrexx PBX running firmware 2.6. Among other connections, four Telekom Germany SIP accounts (multi-device connections) are configured on the PBX.
After an unspecified period of time, individual SIP accounts lose their registration. The affected accounts do not follow any recognizable pattern and it is not always the same accounts that are affected. The PBX reports the following error message for the affected accounts:
Registration failed – Error description: 401: Unauthorized
Triggering a re-registration via the PBX interface has no effect. The registration can only be restored by disabling the affected account, saving the configuration, enabling the account again, and saving once more. After that, the account works normally for some time before the problem reappears.
In addition, a Peoplefone SIP trunk is configured on the same COMtrexx system. This trunk does not exhibit the described behavior and remains registered continuously. Based on my observations so far, the issue only affects the Telekom accounts.
The following points have already been verified:
• SIP ALG is disabled on the ER7406.
• The SIP credentials are correct.
• Different Telekom accounts are affected without any recognizable pattern.
• IPv6 is disabled on the PBX.
• The issue became noticeable after updating the COMtrexx firmware to version 2.6.
To further narrow down the source of the problem, I temporarily replaced the ER7406 with a FRITZ!Box 7590. Apart from the router, the entire environment remained unchanged (same internet connection, same PBX, same SIP accounts).
Since replacing the router, all registrations have remained stable for several days without any failures.
Therefore, I would like to ask whether you are aware of any known issues with the ER7406 related to:
• SIP registrations
• NAT / UDP session handling
• UDP timeouts
• Telekom Germany SIP services
Are there any known findings, diagnostic options, or settings that you would recommend checking?
I would be grateful for any advice or troubleshooting suggestions.
