Thank you Martin. I tried the registry fix. Key Name: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTP Value 9 Name: PPSProviders Type: REG_MULTI_SZ Data: loopback-ppsapi-provider.dll I can confirm that it works. 27 Mar 17:08:48 ntpd[1188]: time_pps_create: loaded 'C:\Program Files (x86)\NTP\bin\loopback-ppsapi-provider.dll'