VPS Customers running Ubuntu 16 or 17 can upgrade to their latest OS version, being Ubuntu 18.04 currently, with the following commands run as the root user:
apt-get update && apt-get upgrade
Then set ‘Prompt=normal’ in /etc/update-manager/release-upgrades and run (as root, preferably on your VPS Console (access to which we provide)):
do-release-upgrade
And answer Y or let it proceed with defaults.
Finally, reboot into your new upgraded kernel and system.
FYI,
Richard.