Serving files and load speeds

Thanks for your work on this great module. I've got it configured ok - files get uploaded to Dropbox as expected.

Originally I thought I'd need 'serve files directly via Dropbox' mode ('public' => TRUE,) enabled as I want to bypass storing any media on my web server but I can't get that to work.

Without 'serve from Dropbox' enabled, it seems to do what I want anyway: only save media to Dropbox. It gives a URL of the file on the Druapl website such as /_flysystem/dropboxexample/...

That's fine, but load speeds are very slow.

So what does 'serve from Dropbox' do? Will that help with load speeds?

When I enable 'serve from Dropbox', the file will upload to Dropbox ok but it will also get duplicated there. Also, while it does work, it doesn't look like it does on the website. The uploaded file will not be previewed on the website after uploading media when adding content (article) on the website. And when I save the article, the node shows a broken image icon and it gives a URL of the file on the Drupal website such as /?itok=x29b8ePG

Incidentally, media that appeared to have failed (in the previous example) will reappear (it will work) as soon as I disable 'serve from Dropbox'

Any advise would be gratefully received. Let me know if you require any more info from me. Happy to provide.