Hello,
Can you please verify if you are using the most recent firmware version for your device? If not, please update to the latest firmware. You can find the firmware available for download here. To update the firmware, access the WebUI of your device and navigate to System -> Firmware -> Update Firmware.
If your current firmware version is older than 7.4, it is recommended to update with the 'keep settings' option disabled. This will erase your existing configuration but will help to avoid any potential migration issues.
In case the firmware update does not resolve the issue, I would like you to replicate the issue by configuring OpenVPN and waiting for a few minutes for the device to attempt to establish a tunnel. Then, download a troubleshoot file. Troubleshoot file can be downloaded from System -> Administration -> Troubleshoot. Please, attach it by editing your question. The attached files are only visible to Teltonika moderators.
Kind Regards,
Andzej