Ok, heres was I got, I'm in the MST time zone.
If NTP server is enabled and I'm in Time Zone MST, Time Zone set to MST, time is 1 hour behind. Even if DST is enabled or not.
If i set Central Time Zone from MST and reboot, the time will be an hour ahead and correct.
Now if i disable DST and use manual time sync from PC, time is correct if I use +30 on Off Set, save settings and reboot the router. Time is correct for MST and remains about 1 minute behind actual time on my PC after checking status after reboot.
Now, if I reboot the router again while using manual sync with PC time, save settings and reboot router, say 5 minutes from last sync with PC, after router reboots, log in and check the time? The time is no longer up to date and reverts back to the last sync of time with the PC.
If I went over 5 minutes and reboot the router, the time reverts back to last sync with PC and time is even more behind from actual time at each reboot.
My 2 cents.