Check your Amazon RDS for SQL Server instance fulfills the following requirements.

Versions 2012 and above are supported

Connect Amazon RDS for SQL Server instances versions 2012 and above to Spotlight Cloud.

Open port 1433

If Windows Firewall is set up to block traffic by default on the Spotlight Cloud Diagnostic Server host then in Windows Firewall | Advanced Settings add new inbound and outbound rules to open port 1433.