Just took an additional moment to look over the settings. Mine were manual, but off by 5-20-30secs between cams, then set to automatic, which meant they all synced, but then jumped off an hour.
This may help ... just found a DST tab
Web interface > Configuration > Advanced Configuration > System
> Time Settings
Check your Time Zone.
Select NTP sync.
Mine is set to the default of: time.windows.com -- ntp port: 123 -- interval: 1440
Then note tab #5 (on my cam with 5.1.6)
> DST
USA:
[V] Enable DST
Start time MAR SECOND SUN 2:00
End Time NOV FIRST SUN 2:00
DST Bias: 60min
Europe:
[V] Enable DST
Start time MAR LAST SUN 2:00
End Time OCT LAST SUN 2:00
DST Bias: 60min
Others:
See google
You can probably do this via iVMS (and maybe a regular NVR) via remote configuration as well. I'm just not near my system at the moment. What would be nice is, if one could set this up once in iVMS and copy the time settings to all the cameras.
Note: After applying DST the time jumped one hour ahead of real time (deep sigh etc) figured maybe it had to reboot to get it right, crossing fingers, one reboot (advanced config > maintenance > reboot) correct time.