Vertech1 - while doing a quick research for WebDAV, I came across this link. I don’t know if this will help you with your issues with Windows 7’s & 8.1’s WebDAV client implementation using HTTPS. I am sure you’ve done your own research when investigating this but thought I’d share it anyway, in the off chance that you didn’t see this somewhere.
http://www.webdavsystem.com/server/prev/v2/documentation/authentication/basic_auth_vista
Edit: Editing this post to paste the contents of that link here directly, for both convenience and in case that link ever becomes unavailable, folks can still find the info here. Contents from above link pasted below:
When developing Basic authentication and using Windows 7 & Vista as a WebDAV client note the following:
Windows 7 and Vista will fail to connect to server using insecure Basic authentication. It will not even display any login dialog. Windows 7 and Vista requires SSL / HTTPS connection to be used with Basic. If you try to connect via Add Network Location Wizard you will get the following error: “The folder you entered does not appear to be valid. Please choose another”. However you still can connect if you set the following registry key on a client machine: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WebClient\Parameters\BasicAuthLevel to 2. The BasicAuthLevel can be set to the following values:
0 - Basic authentication disabled
1 - Basic authentication enabled for SSL shares only
2 or greater - Basic authentication enabled for SSL shares and for non-SSL shares
Unlike Windows XP WebDAV client, Windows Vista may attach a machine or domain name to the user name returned in Authorization header. It separates user name and domain with a single ‘\’ symbol: DOMAIN\User. Make sure you extract the user name correctly from Authorization header.
