the vSphere HA agent on this host cannot reach some of the management network addresses
One more good achievement here.
IT sector is very rapidly developing, at the same time we are facing a lot of problems and resolving as well.
If the host is showing us error –“The vSphare HA agent on this host cannot reach some of the management network addresses of other hosts, and HA may not be able to restart VMs if a host failure occure: IP ADDRESS of HA Host’s”.

The solution is –
Confirm — check the network settings and are they hosts running in the same subnet or not?
Then,
Right-click on the affected host and select the “Reconfigure for vSphare HA” option into the drop-down list.
Wait for some time to re-configure itself, after completion of the process your host will show as normal. In this case, you will not lose any network connectivity for running VM’s.