FN11, Ubuntu VM, Docker "no space left on device"

[Tim1962]

As it says I have Docker running in an Ubuntu Server VM on FN11. So far so good but after playing (i.e. randomly installing/removing Docker Containers for a few days) I get a message "no space on device", either on a Docker CLI or via Portainer and can't now install anything. The VM/Ubuntu is otherwise vanilla with 100Gb size.

This forum and wider net don't provide a solution though google does show some info on similar on Macs etc. Anyone experienced and overcome this?

BW Tim