Unable to add Foglight SQL Server agent to monitor SQL Server instance. It failed with exception "Server returned: Connection reset". It also failed with same error message when adding the instance using shortname, FQDN, or IP address. Login is correct and validated locally on the SQL Server. Telnet to port 1433 is allowed and works as well.

The following error message was seen in the DBSS-Installer agent log:
--- On DBSS-Installer-fglamhostname_YYYY-MM-DD_hhmmss_001.log
ERROR [FglAM:IncomingMessage[5]-77] com.quest.qsi.fason.sqlserver.installer.validation.DBSSDbValidator - Validation failed: cannot establish a DB connection to host MSSQLHOST with profile MSSQLProfile{host='MSSQLHOST', instance= 'DEFAULT_INSTANCE', username='DOMAIN\username', authType= 'WINDOWS_CUSTOM', port= '0' useNTLMv2= 'true', socketTimeout= '900', database= 'master', secureConnection= 'OFF', packetSize= '0', ApplicationIntent= 'NONE', enforceSSLVersion= 'NONE', lockTimeout= '10000', codePageOverride = '' }
com.quest.qsi.fason.framework.connections.common.exceptions.FrameworkException: Failed to establish a SQL-Server JDBC connection protocol to Host [MSSQLHOST\DEFAULT_INSTANCE], user account [DOMAIN\username] . Reason : [[Foglight][SQLServer JDBC Driver]A problem occurred when attempting to contact the server (Server returned: Connection reset). Please ensure that the server parameters passed to the driver are correct and that the server is running. Also ensure that the maximum number of connections have not been exceeded for this server.- Profile:MSSQLProfile{host='MSSQLHOST', instance= 'DEFAULT_INSTANCE', username='DOMAIN\username', authType= 'WINDOWS_CUSTOM', port= '0' useNTLMv2= 'true', socketTimeout= '900', database= 'master', secureConnection= 'OFF', packetSize= '0', ApplicationIntent= 'NONE', enforceSSLVersion= 'NONE', lockTimeout= '10000', codePageOverride = '' }]. . [SQL-Server Error Code = 0. SQL state : 08S01]