I can confirm that Microsoft WebDAV (aka Webclient Service) is not capable to connect with modern secured TLS WebDAV servers. The culprid seems to be SNI. The curiosity: With older versions of Windows (WinXP and Win2003 Server) WebDAV works but only because MS is not checking certs and encryption. Since 2009 with introduction of Win7 they broke their Webclient.
Bottomline: With Windows and WebDAV you’re using an unsecure and not standardized solution. Use Nextcloud Client App or other WebDAV solutions. I suggest Onlyoffice or Collabra running in Webbrowser.