Thanks for your answer.
Yes I tried that and a lot of other things
But before annoying people with logs, I think that I need to confirm something :
TrueNas file-system is zfs
It is often said in the doc that Cloudron needs ext4 ... exclusively ?
Can a nfs share of a zfs dataset work ? Or only nfs share of ext4 dataset (that don't exist on TrueNas) ?
https://docs.cloudron.io/apps/#data-directory
cifs and sshfs volumes are unsuitable as an app's data directory as they do not support file permissions and ownership. mountpoint and nfs volumes may or may not work depending on the destination filesystem.