Well,

Going backwards.

Don't really understand the syntax you provided with the colon.

I changed the docker-compose.yml to a couple of

-/data/joplin-data:/mnt/Joplin

And pulled the file and restarted.

It wails away for a bit and I get an endless;

Killing the process and changing docker-compose.yml back to original now get the same thing.

The odd thing is the daemon is working as I can log in.

Trying to synchronize, I'm told the URL is incorrect.

Checking the synchronization target I get:

Error. Please check that URL, username, password, etc. are correct and that the sync target is accessible. The reported error was:
Not a valid URL: mywebsite.com/api/sessions

Not encouraging.

The folder I want to save everything is /mnt/Joplin

What would the proper syntax be for that?

Thanks