To run PowerCLI cmdlets on vSphere and perform administration or monitoring tasks, you must establish a connection to an ESXi host or a vCenter Server system.
You can have more than one connection to the same server. For more information, see Managing Default Server Connections.
If your login credentials contain non-alphanumeric characters, you might need to escape them. For more information, see Providing Login Credentials.
If you use a proxy server for the connection, verify that it is configured properly, so that the connection is kept alive long enough for tasks to finish.