In a multi-seat environment if you enable PS client plugin and set it to suspend/hibernate the system after a period of inactivity, it will not do so if the PS plugin is not also enabled on the server.

h4. Additional Information
Before checking if the system has been idle and ready for suspend, PS client plugin calls RemotePowerControl.Instance.UserActivityDetected() to inform the server that the client is still up. This call will fail and throw an exception if PS plugin is not enabled on the server, as there is no one listening on the corresponding port (31457)