Hi Peter,
Using the database connector module, you should be able to make secure connections to databases.
Using this connection string, the connection is secured:
jdbc:sqlserver://localhost:1433;databaseName=AdventureWorks;integratedSecurity=true;encrypt=true;trustServerCertificate=true
Or do you want to verify the certificate using the Mendix keystore?
Then you should check the Microsoft Documentation in more detail and you could try to add certificates. Locally, this can be done in settings:
Would the Database Connector module work?
https://appstore.home.mendix.com/link/app/2888/Mendix/Database-Connector