Webdav system error 5 access denied

Server
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1

Accessing to owncloud throug webdav won’t work.
With windows OS, “system error 5, access denied” is encountered after entering credentials.
Running 9.1.2 latest stable.

It worked after fresh install, but now the route is changed to root(https/oc.ourdomain.com) and https is used and webdav don’t work anymore.

using “net use * https://oc.ourdomain.com/remote.php/dav/files/username” ask for user and PW but then “error 5”.

Maybe changin route and https need webdav to be configured?
Server configuration
Operating system: Ubuntu 16.04.1 LTS
Web server: Apache2
Database: MariaDB
PHP version: 7.0.8
ownCloud version (see ownCloud admin page): 9.1.2
Updated from an older ownCloud or fresh install: 9.1.1
Special configuration (external storage, external authentication, reverse proxy, server-side-encryption): changed route and https activated and forced

I will try to set debug mode and find more informations in log files but not really confortable with that yet.

2

Which Windows Version? Anything prior to Windows 8 will fail.
Please run the WebDAV litmus test on your server.

3

I used windows 10, but the problem is the same for others OS.
The litmus test gave me 2 problems:
2. Options: Waning: server does not claim Class 2 compliance
18: propget: Fail (Property {http://example.com/nenon/litmus/}high-unicode had value, expected )