VMware ESXi
When an ESXi management IP address is changed and if it fails to connect to the vCenter then restart vCenter agent and management agents on ESXi host.
Workaround:
Before proceeding, ensure that:
To change the ESXi server management IP address:
Use DCUI Change ESXi Server Management IP Address:
Log in to the Direct Console User Interface of the vCenter Server Appliance.
Select Restart Management Network and press Enter.
Press F11.
You can adjust other options to ensure that HA does not activate for a momentary disconnect from vCenter Server instead of a host failure, resulting in failure of virtual machines. For example, the key feature is Datastore heart-beating. If this feature is enabled, virtual machines are identified as running on the ESXi host and HA does not activate. You can also adjust the host monitoring or network isolation responses while making changes.
Note: This is the safest and simplest method:
4.Change the IP address and update the DNS server.
5.Add the ESXi host back to vCenter Server.Then restart VC management network and ESXi host management agents.Note: If you are using syslog on your host you may also need to restart the syslog service to prevent log entries from using the old management IP information of the host by running esxcli system syslog reload on the host.