Maybe default port was changed. In that case you need to update the connectionstrings used by the monitor app.
Message: "Error: QVX_UNEXPECTED_END_OF_DATA..." This error can have different causes.
Customized proxy port
Possible cause The proxy's HTTPS port has been customized.
Proposed action Change all the monitor_apps_REST_ data connections to use the customized port.
Example: CUSTOM CONNECT TO"provider=QvRestConnector.exe;url=https://localhost:4443/qrs..."
Do this for all monitor_apps connections.