For years we synced Dropbox via the API and rsync to your TrueNAS.
There we took daily snapshot and got a pretty good versioning system by doing so.
It always took pretty long, because the API performance of Dropbox is pretty poor, but now it is no longer working at all. We run into the error:
Error (504)Something went wrong
I will try to turn some nobs in regards to simultanious transfers, but I guess it is game over.
I donβt think either rclone or the Dropbox API support sessions of that extended duration, and the API endpoint is closing the session, resulting in the 504 error. You should break your backups into multiple segments.