I've been finding that my device recently has been unable to connect to ntp.ubuntu.com with its systemd-timesyncd
service.
Mar 15 00:31:52 l157 systemd-timesyncd[673]: Timed out waiting for reply from 91.189.89.199:123 (ntp.ubuntu.com).
Mar 15 00:32:02 l157 systemd-timesyncd[673]: Timed out waiting for reply from 91.189.89.198:123 (ntp.ubuntu.com).
Mar 15 00:32:12 l157 systemd-timesyncd[673]: Timed out waiting for reply from 91.189.91.157:123 (ntp.ubuntu.com).
Mar 15 00:32:23 l157 systemd-timesyncd[673]: Timed out waiting for reply from 91.189.94.4:123 (ntp.ubuntu.com).
Is ntp.ubuntu.com a viable NTP site to use for this or should I be using another NTP site?