There is a bug in vSphere 6.0 Update 1b that could give som false warnings, like “Host cannot communicate with all other nodes in the Virtual SAN enabled cluster”.
The problem and solution can be found in this KB: http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=2143214
One of my colleagues tried this but it does not always work, and we had to leave the customers installation with a.”you just have to ignore the warnings until VMware releases a patch”.
But false warnings in your infrastructure can make you blind to serious problem!
In a community forum thread, about this issue, vSAN guru Cormac Hogan has encouraged all to file a Support Request referencing “internal bug reference 1587500”. https://communities.vmware.com/thread/528231
Thanks to my Colleague Anders Jacobsen for clarifying this issue, and my other Colleague André Briand de Crèvecoeur who wrote about it on linked in: https://www.linkedin.com/pulse/host-cannot-communicate-all-other-nodes-virtual-san-andr%C3%A9?trk=hb_ntf_MEGAPHONE_ARTICLE_POST