First of all, this is not a request for help but something i wanted to share with everyone else because i won’t be the only one trying to achieve the same result.
Problems i’ve run into before:
While starting the bitwarden server on a new server with the backupped data it refused to work. Let’s Encrypt caused an error because it expected some symlinks to files that do not exist anymore. And if the i remove the data from the lets encrypt server the installation will boot but the web interface doesn’t work.
How to restore BWDATA to another server without problems:
Install Docker and Docker Composer
Run a new installation and use your old installation ID and key (can be found under bwdata/env/global.override.env from backup)
Make sure to use the same domain and settings.
When finished stop the service and copy you bwdata backup into the new bwdata folder except for the letsencrypt folder
Now start bitwarden and everything should work correctly