2. Is DNS resolvable for the server?
3. Have you tried running configureforansibleremoting.ps1 with the extra arguments to recreate the winrm certificate?
4. Is the Windows server a VM cloned from a template?
5. What pywinrm version?
"On Windows 7 and Server 2008 R2 machines, due to a bug in Windows Management Framework 3.0, it may be necessary to install this hotfix http://support.microsoft.com/kb/2842230 to avoid receiving out of memory and stack overflow exceptions. Newly-installed Server 2008 R2 systems which are not fully up to date with windows updates are known to have this issue.
Windows 8.1 and Server 2012 R2 are not affected by this issue as they come with Windows Management Framework 4.0."
Hope this hlps,
Jon