Cannot download from WebDav Error 0x80070780

I setup WebDAV on a Win10 machine (server). From another Win10 machine (client) I mapped to the server via "Add a network location" in windows explorer. This successfully created the connection. I can list files, upload files, create directories, see file attributes. However, when I attempt to download a file (i.e. on the client I attempt to retrieve a file from the WebDAV server) I get the following error: Error 0x80070780: The file cannot be accessed by the system.

Researching this error I've found lots of information about this error when attempting to upload to the server, but nothing about when downloading.

I expect this is an issue with Win10 on the client because I'm able to download with 3rd party software (Cyberduck). I get the same error on a different Win10 machine as well.

Other details:

• Connection is https
• I have a valid certificate from Let's Encrypt
• The connection is to a sub domain and sub folder (e.g. https://sub.mydomain.com/webdav)
• User logs into a local (to the server) account

It appears that this was actually on the server side. For some reason Explorer requires the permission "Source" while the 3rd party software doesn't. I'd be love to see another answer explain why this is.

To set this permission:

1. Open IIS Mananger
2. Select the WebDAV site or folder
3. Open "WebDAV Authoring Rules"
4. Edit the pertinent rule
5. Ensure the "Source" box is ticked and click "OK"