Docker container won't start on new host - problems to find reason

I got a new machine setup (no planned migration) to run my docker container. I’ve always been using volumes for /var/www/html and an external MySQL server. Backup for those data available (but no standard NC backup).
Unfortunately, it’s not possible to run the container anymore.
I’m using docker-compose with standard options - image ‘nextcloud’, map vol to /var/www/html, set dns, ports and container name, has always been working fine like that. When trying to run the container, it will exit after just about 3s with no error message or anything. Unfortunately, ‘docker logs cloud’ just shows no output at all (in opposite to all other containers running). Is there any way to find out, why nextcloud won’t come up? Connection to DB seems to work (at least I get some error stack trace in the logs when using wrong parameters). Would be great if you could give me some hints how to debug that situation. TIA!
I know, I’m not giving lots of information but everything is kind of standard here… and I’m not getting any error logs.