Hi,
a CDN is made for basic webpages and not for advanced file sharing solutions like ownCloud. Please disable this CDN for ownCloud as you will see other issues like explained here:
https://doc.owncloud.org/server/9.1/admin_manual/issues/general_troubleshooting.html#other-issues
https://doc.owncloud.org/server/9.1/admin_manual/configuration_files/big_file_upload_configuration.html#general-upload-issues
If you still have issues you can work your way through this FAQ:
If you encounter the following scenario:
You can access your owncloud web interface
The owncloud sync client as well as WebDAV (via some WebDAV client, or a direct access in a browser via http://yourowncloud/remote.php/webdav ) aren't working (typically you will see a 401/403/405 error in the logs)
You're getting a message "Your web server is not yet properly setup to allow files synchronization because the WebDAV interface seems to be broken. Please double check the installation guides."
Th…