NTP is Network Time Protocol and is used for networking devices to synchronize their date and time to global servers, making sure all devices automatically have the right time set up.
NTP is very important for Nebula devices. If NTP is not correct on the device, issues will be visible in NCC possibly by no data shown, device offline, wrong configuration.
NTP (UDP/TCP 123) always needs to be allowed from the LAN side to WAN when you are using Nebula devices. NCC server and your nebula device are using Coordinated Universal Time (zone) (UTC) +00:00. Do not adjust it to the local time zone, this can only lead to the issue.
Nebula devices sync automatically in these scenarios.
When the AP boots up and NTP sync successfully.
Sync again after 6 hours.
NSW & NSG
When the NSW & NSG boots up and NTP sync successfully.
Sync again after 24 hours.
If the Nebula devices fail NTP sync, it will be triggered again after 30 seconds.