When trying to connect to localhost or Spotlight Diagnostic Server in the Tools | Options | Spotlight Essentials | Configure Diagnostic Server | Select / Enter Diagnostic Server Host, the following error is displayed:
"Unable to locate specified host. The diagnostic Server on host (servername) could not be contacted"
localhost - Diagnostic Server has not been installed
Spotlight Diagnostic Server - Spotlight DS cannot be shared with Toad. The reason being is that they are configured differently ie. the SOSSE DS does monitoring and diagnosis, whereas the Toad for SQL Server DS is configured only for collecting performance data.
In the Tools | Options | Spotlight Essentials | Configure Diagnostic Server | click on Install button in the Install a New Diagnostic Server. Go through the wizard to install.
Please see KB article 133512 for steps to install Spotlight Essentials for Toad for SQL Server.