has problems with some destination servers on 2.0.6.1, but 2.0.5.1 uses older code without this problem.
You can look at your About screen to see what you’re running, and System info if you need more detail.
SFTP problems like I’m thinking of usually result in extreme failure though, not just slow upload. Problem:
Release 2.0.6.1 (beta) 2021 - SFTP failure (Synology) describes it, but I don’t hear you get that message.
SFTP also means you can use clients such as WinSCP if you need to look over remote files and have no simple other way. FileZilla and Cyberduck are other GUI options. Windows even has a CLI sftp command.
It’s not supposed to, because
“all” means DB + destination which must match DB and which could recreate DB if all the files are there.
You should be able to delete the destination files using tools I mentioned, but before delete you could look.
Typically a GUI display can sort columns, so you could sort by date and see if you ended on a dlist or not.