Hi Laurent
Generally the device appears to be going through the sync process in an endless 24hr loop, where a few thousand records in, it self-cancels and then after that starts all over again. On a fresh installation not a single note gets downloaded.
I have followed your previous advice to turn off auto download of attachments and images.
Sometimes this error message is shown: "Could not acquire sync lock."
Have done fresh installs from scratch, after a restart on all devices. Even on two devices a full factory reset.

I love the wonder that is Joplin by the way!