Found this link Windows 7 Fixing The Mapped Drive Credentials Problem | The Gadget Grill and found it interesting. BUT, made no difference.

Okay, I deleted the mapped drives and related credentials. I rebooted, re-added the mapped drives to both the IIS7 and QNAP servers. Both worked perfectly. I rebooted and again and tried to access...

Nope. I deleted the credentials related to both servers (yes, were WIndows credentials). I used the existing mapped drives, it asked for ID and password, and failed first time and every time for...

An update: Webdav using SSL works to access my IIS7 server even after a reboot. HOWEVER, after a reboot it always prompts me for sign in credentials the first time I access it no matter how many...

Since Windows update on 11/12/2015 (mess of cumulative updates) I can no longer connect to my QNAP Webdav shares. I have a HP laptop running Windows 10 Pro over wifi and am connecting using SSL.
The...