Ensure that any external or Windows/Linux firewalls between the Console and the harvester allow ports 161 and 3308 to allow the Watchdog Service to Poll all of the NFA Servers.
For a full list of ports that need to be open between NFA servers please review the link below:
Once the MySql connection is opened up, the error may persist.
To resolve this, on the NFA Console server, open a command prompt and run:
truncate table harvester_status;
Then restart the Netqos ReporterAnalyzer Watchdog service, and wait a few minutes, then refresh the NFA System Status page.