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Troubleshoot an unexpected router reboot

A DrayTek router can keep running for a long time in normal operation, and you can check the current system uptime at Online Status >> Physical Connection.

a screenshot of DrayOS online status

If the system uptime is lower than expected, it means the router has ever run into a reboot event. In this article, we will provide some steps to troubleshoot an unexpected reboot event.

1. Figure out if it is a planned reboot

The network administrator could arrange a reboot, and we may check if the router has the schedule reboot configuration in the System Maintenance >> Reboot System page or one of the following actions have been taken during this time.

  • Firmware Upgrade by GUI, Firmware Upgrade Utility or ACS server
  • Configuration changes by GUI, Telnet, SSH or ACS server and one of the changes requires a system reboot
  • Reboot by GUI, Telnet, SSH or ACS server
2. Remove the connected USB devices

A broken USB device may make Router run into a reboot event. We may remove the connected USB device while meeting an unexpected reboot event.

3. Check the Power supply

Check that the power supply used with the router supplies the correct voltage and amperage to match the Vigor router's listed Power Consumption shown on the label on the underside of the router.

4. Check Router’s Debug Log

Vigor Router will leave some debug logs while meeting an unexpected reboot event, and we may check if that log is available or not by entering the command sys ver dbg from Telnet, SSH or Web Console. Below is an example for the debug log.

a screenshot of the debug log

When seeing the debug log, we shall check if the Firmware Version and the CURRENT_VERSION is same (The RC wording in CURRENT_VERSION could be ignored.) If they are not same, it means the debug log may be generated by a reboot event from an earlier firmware version. Please use the command “sys ver dbg reset” to clear the current log and collect the new debug log again after a new reboot event occurs.

You may also consider to enable the Mail Alert feature in System Maintenance >> SysLog / Mail Alert Setup page and select Debug Log. Then Vigor Router will send the debug log to the specified mail address automatically after it recovers from an unexpected reboot event. enable mail alert for sending the debug log

For Vigor3910/2962, please go to Diagnostics >> Debug Logs. Select Full Logs and click Download.

5. Email to DrayTek Support

Please provide the following information to DrayTek Support when you meet an unexpected router reboot event.

  • Router Debug log if it is available
  • A backup config file of Vigor Router and the login password
  • Syslog which contains the reboot event and the date/time when the reboot occurred
  • Detailed information about the applications or activities in use prior to the unexpected reboot; Being able to reproduce the issue locally would greatly help accelerate troubleshooting and problem resolution.

A DrayTek router can keep running for a long time in normal operation and the current system uptime of the router can be found on the Dashboard.

If the system uptime is lower than expected, it means the router has ever run into a reboot event. In this article, we will provide some steps to troubleshoot an unexpected reboot event.

1. Figure out if it is a planned reboot

A planned reboot could be arranged by the network administrator, and we may check if the router has the schedule reboot configuration in the System Maintenance >> System Reboot page or one of the following actions have ever been made at around the time.

  • Firmware Upgrade by GUI, Firmware Upgrade Utility or ACS server
  • Reboot by GUI, Telnet, SSH or ACS server

    • 2. Remove the connected USB devices

    A broken USB device may make Router run into a reboot event. If unexpected reboot events occur, it is recommended to disconnect all connected USB devices and then continue monitoring the router status.

    3. Check the Power supply

    Check that the power supply used with the router supplies the correct voltage and amperage to match the Vigor router's listed Power Consumption shown on the label on the underside of the router.

    4. Check the Notification Log

    Check whether there are any unusual events in the notification log before the reboot occurs, such as WAN disconnection, or messages like coredump was generated.

    5. Collect the Router’s Syslog

    Please install the Syslog Utility on a local computer to collect the syslog before and after the router reboot issue occurs.

    Using a USB disk for log storage is not recommended, as the logs may not be written to the disk in time before the reboot happens.

    Please refer to the following article for instructions on collecting the router’s syslog:

    https://www.draytek.com/support/knowledge-base/5746#DrayOS5_section

    6. Collect the Router’s Debug Log

    The Vigor Router will generate debug logs when an unexpected reboot occurs and store them internally. The debug log can be downloaded from the router’s Web UI via Utility / Debug Logs. After clicking Download, the log file will be saved to the computer. Please note that the debug log file is not intended to be extracted or uncompressed.

    7. Email to DrayTek Support

    Please provide the following information to DrayTek Support when you meet an unexpected router reboot event.

  • Router Debug log and the date/time when the reboot occurred
  • Syslog which contains the reboot event
  • A backup config file of Vigor Router and the login password
  • Detailed information about the applications or activities in use prior to the unexpected reboot; Being able to reproduce the issue locally would greatly help accelerate troubleshooting and problem resolution.

    • Published On:2026-05-28 

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