Docker stops working when changing to devicemapper for collabora

Hey everyone,
newbie nextclouder here…

I successfully installed nextcloud on a VPS (Ubuntu 16.04 LTS) and was trying to install Collabora as well.
After changing docker to “devicemapper” (via daemon.json or systemd), docker stopped working. Every docker command (e.g. docker info) hangs and is not returning anything. I needed to stop every docker command with ^C.

Anybody an idea how to solve the problem? Without changing to devicemapper I can install and run collabora but can’t use it with a document.

Thanks for you help