NTP stops serving time when reference is lost

Symptoms

• NTP clients stop receiving responses after the device loses its reference (GNSS, PTP, upstream NTP, or time code)
• NTP service works while locked, but stops when the device becomes unlocked or enters holdover

Causes

• Time dissemination during reference outages is disabled, the device stops serving NTP to avoid distributing potentially inaccurate time
• A dissemination duration is configured and has expired, so outputs are intentionally disabled after a set time in holdover

Troubleshooting steps

1. Enable time dissemination during outages. In WinDiscovery, open Device Settings → Output Control and check Allow time server during reference outages.
2. Set the duration appropriately. Set Duration time server is allowed to 0 only if the application permits indefinite holdover. Otherwise, use a duration consistent with the application’s accuracy requirements.

   Warning: Clocks without a reference are prone to drift. Time may remain stable, but inaccurate compared to known-good references.

3. Confirm expected status. During reference loss, the device may show Unlocked or Holdover while still responding to NTP. This is expected when dissemination is enabled.
4. See the reference article for details. Time Dissemination During Reference Outages