Dahua Cameras Lose GMT Offset

[DDDRelic]

I have four IPC-HDW4231EM-ASE cameras, and one IPC-HDW2231R-ZS camera, and all cameras reset their GMT offset from GMT+12 (New Zealand) to GMT+0 at 08:00 local time daily.
Their time is synchronised to a NetTime app (version 3.14) running on the Blue Iris PC, and the app always shows the correct time even when the cameras have changed the GMT offset.
The time is consistent and correct across all cameras if one ignores the GMT offset changes.
The cameras have "AutoRestart" set to never, and I can't find anything in the BI logs to indicate what is happening.
If I look at the BI recordings (set to 24x7) around the 08:00 period I can see all cameras flicker to black and back again with the time changed (too short to be a camera reset), so something is telling the cameras to change the GMT offset but I just don't know enough to figure out what.
Can anyone suggest where to look next?

 

[looney2ns]

Did you open port 123 in the windows firewall so the cams can actually connect to NetTime?
Proper IP in the cams to the NetTime computer?
You disabled Windows Time?

 

[DDDRelic]

Hi looney2ns , firewall and IP is OK, the cameras are connecting to NetTime. Not sure how to disable Windows Time.
I set NetTime logging to debug, and captured events around the 08:00 period as in the snapshot below.
The log shows the 5 minute syncs for all cameras occurring until 08:00 where there is another set of time updates that are out of step with the normal 5 minute updates.
After that has happened the cameras settle down to the normal 5 minute syncs again, albeit with different times to those before the 08:00 event.
So, something happens at 08:00, I just don't know what.

 

[DDDRelic]

I think that the issue is fixed (cross fingers, touch wood etc) but not necessarily solved.
Yesterday after a bit of googling I checked the status of Windows Time as looney suggested, and found that the server was disabled, only the client was enabled so all good.
I then upgraded the 4 IPC-HDW4231EM-ASE cameras as in my googling I noted a reference to fixing a GMT bug relating to the current firmware.
That may have done something as I didn't see any 8:00AM reset occurring in the NetTime logs this morning (an previous example of which is shown above).
I also found an anomaly in the behaviour of Dahua's SmartPSS software.
I had been using the software as an easy way to talk to the cameras and reset the GMT offset. This actually worked as I could see the time change on the video from the cameras and the time was OK until the next 08:00AM event when the GMT offset was reset again.
After upgrading each camera I reset them to defaults, and used their web pages from within SmartPSS Device Config page to reapply my desired settings that had been wiped.
While doing this I discovered that if I set the GMT offset within SmartPSS Device Config page and save the setting, then had a look at the setting using the camera web page, the GMT offset showed as NOT having changed.
Therefore the next time an 08:00AM event occurred the incorrect GMT offset would be loaded.
Setting the GMT offset from within the camera web page DID result in a permanent setting.
So, it is early days yet but I have not seen the 08:00AM event again, and if I check in the cameras the correct GMT offset is still there.
I am still puzzled over what the 08:00 event was and why it affected the IPC-HDW2231R-ZS if it was nothing but a firmware issue on the IPC-HDW4231EM-ASE cameras.
I guess I'll just have to wait and see how things go now.