If you're trying to add MS SQL Web or Standard to your server, you must enable the SQL Server Browser service so that Plesk can recognize the database server.
- While logged into your server with Remote Desktop, open Administrative tools from the Start Menu.
- Double-click Services to open the services menu.
- Right-click on SQL Server Browser, then click Properties.
- Toggle the Startup Type drop-down menu to Automatic.
- Click Apply to save the changes.
- Click Start to start the service.
Next step