After upgrading to Data Center Security Server: Advanced (DCS) Version 6.9.2 all communication with the legacy agents were lost and went 'Offline'
Release : 6.9.2
Old operating systems like Windows 2000 or Windows NT are not compatible with SHA256 and therefore need SHA1 certificates
1. Stop the DCS Manager services
2. Copy the server.xml file from the last DCS Manager version into '<install directory>\Symantec\Data Center Security Server\Server\tomcat\conf' directory of the newly upgraded DCS Manager
3. Start the DCS Manager services and confirm the agents are starting to report back online