[Markismus]

Well. I think your testing is solid.

The user/pass seems a red flag: Functionality is bound the be dependent on it. Why don't you try getting that to work.

Another approach: Install Total Commander. Among other things it allows you to browse your files and to send them to the other device via BT. This way you can test whether the note files work on other devices. If they don't work, it's no use syncing.