ChangeAuditor Agents going inactive after a period of first falling back to Coordinator indirect mode.
This may be caused by DNS issues that make it hard for the Agents to connect directly to the SQL Server using either the FQDN or the SHORTNAME of the SQL Server.
First, look at the Agent logs and see if the Agents are falling back from SQL Direct to Coordinator Indirect mode and then later, completely loosing the connection to the Coordinator (the Coordinator may simply have too many Agents connecting via Coordinator Indirect mode and may not be able to sustain these connections in the long term).
To see if this is related to DNS or not, try putting the IP Address instead of either the FQDN or the SHORTNAME of the SQL Server in the ChangeAuditor Database Configurator tool.
On your ChangeAuditor Coordinator machine, right-click on your ChangeAuditor Coordinator icon on the lower right task bar, and click "ChangeAuditor Database Configurator...", in here, you can change the SQL Server name from the current name to it's IP Address instead and restart the service when prompted to do so after pressing "OK".