So while fumbling about on my VPS I somehow managed to disable all networking. Using the VPS console I noticed this in /var/log/syslog:

virtio_net virtio0 ens3: renamed from eth0

That doesn’t sound good. Sure enough, trying:

ifup eth0

Returned:

Failed to bring up eth0

Certainly explains the lack of network.

After some digging about on the net I edited /etc/network/interfaces and changed all eth0 references to ens3. A quick reboot and everything is back in action.

I don’t know if it will revert back to eth0, or if this is the right action to take, but so far so good.

A follow-up note. After upgrading the kernel on my VPS I had to revert the above change as the device had gone back to eth0.