When you specify an NTP server, synchronization between the NTP server clock and the appliance clock might not be immediate.
If the NTP server clock has an earlier date or time setting than the appliance clock, the system will slow down the appliance clock until the two are synchronized. This provides for proper incrementation of log files and other time-sensitive information during the synchronization process.
If the NTP server clock has a later date or time setting than the appliance clock, synchronization between the two will generally be immediate. However, in certain situations you might observe the appliance clock incrementing by 600-minute intervals. This is normal system behavior.
IMPORTANT: The Apply button changes from Wait back to Apply. This indicates only that the NTP configuration change has been made, not that the appliance clock is fully synchronized with the NTP server.
If necessary, you can set appliance time manually to the target time and then re-enable the NTP feature.