Clients cannot sync to the NTP server

• NTP clients do not synchronize to the server
• Clients report no response or unsynchronized status
• NTP synchronization worked previously and has stopped

• Client configuration or reachability issues
• Compatibility settings affecting packet acceptance
• Upstream reference unavailable or unstable

1. Confirm the server is reachable from the client.
2. Verify the client is pointed at the correct server address.
3. Check any dissemination or compatibility settings that could affect client acceptance.

1. From the client, verify basic reachability (ping/routing) to the NTP server IP.
2. Ensure UDP port 123 is permitted between the client and server.
3. Ensure the client is configured for standard client mode. Some Masterclock devices do not support authentication or symmetric active modes.
4. Verify the server is configured to serve NTP (Output Control) and is not in an alarm state that causes clients to reject it.

Time Dissemination During Reference Outages