A host has been isolated from the network in a HA cluster. Since an isolated host cannot be distinguished from a failed host except by the isolated host itself, this event is logged when the isolated host regains network connectivity.
Host can no longer communicate with other hosts in the cluster. The host failed to to ping its isolation addresses.
Check host network connectivity and try to reconfigure HA.
If you ensure that your network infrastructure is sufficiently redundant and that at least one network path is available at all times, host network isolation should be a rare occurrence.
See the vSphere Availability Guide for more information.
Refer to the VMware Online Documentation for more information.