During the Agent update process, an Agent may appear to be disconnected for a few minutes. This is normal since associated Windows services need to be stopped, the update must be performed, and Windows services need to be restarted. However, if the disconnection lasts for longer than a few minutes, the Agent may actually be disconnected.
If after five minutes, the Agent still hasn't reconnected, right-click the Agent in the Peer Management Center and select the Restart Agent Service option. This will attempt to restart the service using a Windows service control (SC) command. However, this will only have an impact if the Windows server where the Peer Management Center is installed can directly access the Windows server running the Agent.
If the Agent still fails to reconnect, a remote desktop connection to the Agent's server will be necessary to attempt to restart the Agent service, and if necessary, to reinstall the Agent manually.