Can they query ntp? Ping being ICMP and ntp being UDP sometimes firewall rules get in the way. You can try and manually run the ntp-check task to see if the problem persists or it might contain a better error message.
Can they query ntp? Ping being ICMP and ntp being UDP sometimes firewall rules get in the way. You can try and manually run the ntp-check task to see if the problem persists or it might contain a better error message.