If you’re facing the error shown above during enrollment, this error typically occurs when the TC Bar cannot establish a secure connection to the Sennheiser Cloud services due to one or more of the following reasons:
1. Make sure that the network to which the bar is connected has access to the internet.
Also, verify the selected IPv4 mode. In Automatic (DHCP) mode, the device receives DNS settings from the network.
When switching to Manual (static IP), DNS is no longer provided automatically, and must be configured manually. Missing or incorrect DNS settings can prevent cloud connectivity and cause enrollment to fail.
2. Check the device time
The time on the device may not be correct, you can see the time that the device is using in the Maintenance Tab under System time:
Fig. 1: System time if NTP is off - this can be edited or the browser time can be taken by clicking the button
Warning: this will be reset to its initial state after each reboot of the device (can be used for testing, but not recommended as a permanent solution)
Fig. 2: System time if NTP is On – for further explanation check the next section
Normally, no time issue should occur with the default configuration — however, it is recommended to verify the selected mode if time synchronization fails.
In the most recent firmware update, two default NTP servers are preconfigured in Manual mode and provide correct system time in most cases.
Users may overwrite these servers manually. When switching to Automatic, the device attempts to obtain time from the network via DHCP/NTP.
Switching back to Manual restores the default NTP servers automatically.
Lastly the device does not validate whether configured NTP server URLs are functional; users should ensure the servers provide valid time.
Note: The System Time is displayed in UTC (UTC+0). This may differ from the local browser or operating system time.
NTP Settings
Fig. 3: If you turn on NTP you can choose between two settings: Automatic or Manual
Automatic: if you switch to automatic and an IP address is displayed in the NTP server field it means that this was provided by your DHCP server – this is not always providing the actual time, so you have to be sure that this is working correctly (check with your IT administrator if you are unsure).
Manual: Two NTP servers will be in place, this can of course also be set freely to an openly accessible one or your own.
3. Check your firewall settings:
The device needs to be able to reach the following IPs:
All device communication is secured with current TLS/SSL.
Your TC Bar device is automatically assigned to an IoT region based on its public IP address to ensure minimal latency and optimal response times. Therefore, your firewall only needs to allow the port and IP address corresponding to your assigned region.
Currently, only direct connection (MQTT over WebSockets; port 443) is supported.
The connection type “behind HTTPS proxy” is not supported by the TC Bar. The URLs provided are for reference only.
If you are using a mobile connection to the internet, also make sure that the mobile provider is allowing all required outbound communication.
4. Try updating the firmware again
If none of the above steps have helped to solve your issue, try updating your firmware again to the same version using the Local Web UI.
Click on “Get update” under the current firmware version:
In the popup that opens, you can either select the firmware file using the “Browse files” button or just drag the firmware file to the window.
After clicking on “Upload file and run update” your bar should update and reboot at the end.
Just a reminder: if you have set the time on the device by clicking the “Use browser time” button in the steps before, you will have to set the time again after the reboot.