Using NAT between the vCenter Server system and ESX/ESXi hosts is an unsupported configuration.
vCenter Server requires port 902 UDP for heartbeat functionality. Even when this port is open, the host may still disconnect if the firewall on Windows Server 2008 blocks Edge Traversal.
To resolve this issue, you must enable the Allow Edge Traversal option.
To enable the Allow Edge Traversal option:
- In Control Panel, open Administrative Tools.
- Click Windows Firewall with Advanced Security.
- Click Inbound Rules.
- Locate and double-click the VMware vCenter Server - Host heartbeat rule.
- Click the Advanced tab.
- Select the Allow Edge Traversal option.
- Click OK.
Note: You need not restart the services for the changes to take effect. However, you may have to remove and readd the ESXi host that was disconnecting.
For related information, see: