Unable to establish CIM session with ESX server: The remote server returned an error: (501) Not Implemented.

Looking in 

cat /var/log/messages

We see Cipher Errors , SHA-1 was decomissioned in window with a windows update

Ciphers Support : https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1018510

4.1 is Out of Support as of Last year : https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2039567

Need to update Vmware