ESX Service Console Gateway Address and VLAN not reachable:
What is the SEARCH-String for getting the information about the affected ESXi-Servers - who can not find their ServiceConsole Gateway-address, anymore?
vSphere HA Agent on this host could not reach isolation address: 140.xx.xx.6
Perform a traceroute too. If this is a vlan, you need to route that packet going to another VLAN. You can think of it as another subnet.
Both searches are useful:
sv* isolation address* | stats count by host
sv* 140.xx.xx.6* no reply from* | stats count by host