The purpose of this document is to understand the reason of the alert and clear it in Cloud vCenter.
"vSphere HA agent on host cannot reach some management network addresses of other hosts" warning is seen in Cloud vCenter for one or more hosts.
These are the notifications sent upon the occurrence of an event, when a host experiencing an HA event cannot ping or reach the Management Network IP address of other hosts in the cluster, possibly due to firewall rules, an incorrect Management Network IP, use of IPv6, or other network connectivity issues.
Also, these are triggered when a host goes down due to various reasons. When there is a change in the Master Host. However, in case of any impact on the vSphere HA because of this event, HA will be reconfigured at Host level for the affected host.
For any clarifications and issue troubleshooting, file a Support Request. For more information, see How to file a Support Request in Customer Connect (2006985)