[Mashiro]

Linux stores logs usually in /var/log unless you have configured it otherwise. Depending on the application there might be a folder inside /var/log with the application name where the logs are stored (e.g. /var/log/openvpn) or simply a single log file where everything is stored (one example is /var/log/syslog).

I would recommend to look into OpenVPN logs if available but also syslog and other available logs. And also check journalctl and systemctl status.

Something must have happened during the update that either broke the server or changed something elsewhere.