I did remove my docker completely using:
rm -rf /srv/dev-by-.../Docker (same as Docker storage in OMV-Compose)
apt purge docker* (to fully remove any docker packages)
rm -rf /etc/docker (to remove any remaining files, as apt outputs that it did not delete the directory as its not empty)
Then i (re)installed docker using the OMV-Compose GUI and now the networking issues are gone.
Interesting, good to know. Thank you.