Hi Community,
we solved the problem.
This issues was related to a bug in vmWare: see articles below.
BR
Torsten
https://social.technet.microsoft.com/Forums/office/en-US/9807a799-bea3-46ad-92a5-732779135f98/problems-accessing-administrative-shares-remotely-windows-cannot-access-servernamesharename?forum=winserver8gen
https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1012225