To set the NTP Server
This feature is supported in SonicOS 8.1 and higher versions.
Click on the Settings screen, to use the manually entered list of NTP servers to set the firewall clock rather than the internal list of NTP servers, select Only use custom NTP servers.
Select this option only if you have configured one or more NTP servers. For more information about NTP servers, see Configuring NTP Servers.