As this is the top result in Google for "unraid ntp not working", I'll share my problem (and solution) that happened with two systems: due to a specific VLAN configuration, I had two network adapters (eth0 and eth1) so that eth0 was physically disconnected and eth1 contained only VLANs. The NTP service does not seem to be able to find its way through to the Internet (community plugin downloads etc. do work). I connected a cable to the eth0 and disabled VLANs (for eth0), and now NTP works.
