Obtain the server hostname or instance endpoint, database name, supported authentication method and required encryption settings. Create a dedicated application database user with appropriate permissions. Keep credentials in protected application configuration rather than a public file or repository.

1. Open the Plesk database entry and confirm its engine and server. Record the exact database and user names; do not assume every database uses localhost.
2. Configure the application supported SQL Server driver or provider. Use the intended hostname and port or instance syntax from the service configuration.
3. Set the authentication method deliberately. SQL authentication uses an assigned SQL credential, while Windows integrated authentication depends on the actual application identity and server trust arrangement.
4. Enable the required encrypted connection with a server certificate trusted by the application host and matching the hostname. Do not make certificate-trust bypasses a permanent production setting.
5. Test from the application environment with a harmless query, then a controlled application operation requiring its normal permissions. Avoid using an administrator or sa credential as the routine application login.

Through an authorized diagnostic using the application's actual SQL Server connection, run:

SELECT DB_NAME() AS database_name,
       USER_NAME() AS database_user;

This reads the current database and database-user context without changing tables. Compare them with the database and identity assigned to the application. An administrator connection in a separate management tool can return different values and does not prove that the application uses the right credentials.

A successful result establishes a connection and its context, not every permission the application needs or the complete TLS configuration. Continue with one controlled normal application action and verify the encrypted connection settings separately. Keep names and diagnostic output private, and remove any temporary web diagnostic after testing.

Confirm successful reads and intended writes, correct database selection and no unnecessary access to other databases. Review application and SQL Server logs for authentication or TLS errors. Test again after an application-pool recycle so hidden interactive-session credentials are not masking the setup.

For timeouts, investigate network reachability, listening endpoint and scoped firewall access. For login failures, inspect authentication mode, database mapping and user permissions. For certificate errors, fix trust and hostname consistency. Do not open SQL Server to every internet address or grant sysadmin privileges to bypass a configuration issue.

• Creating a website database in Plesk
• Adding a database user with appropriate permissions in Plesk
• Planning SQL Server database backups on Plesk for Windows
• Diagnosing SQL Server application login failures

• Plesk: Accessing Databases
• Plesk: Managing Database User Accounts

• SQL Server DB_NAME
• SQL Server USER_NAME