Update: following this suggestion https://community.n8n.io/t/fresh-docker-installation-on-ubuntu-gives-404-page/3308/5?u=lstnadmin it was enough to change the path in the docker-compose file
From
- ${DATA_FOLDER}/.n8n:/home/node/.n8n
to
- ${DATA_FOLDER}/.n8n:/root/.n8n
And then restart
Case closed, Watson 