All Interfaces build using the Interface Builder should be secured by SSL without any additional modification.
For interfaces created using MetaLocator's Legacy Interface Editor, as indicated by the blue Edit button, customers can control whether SSL is enabled. Many years ago, SSL was not enabled by default, so you might find an old interface showing mixed content warnings or connection issues.
To enable SSL for for interfaces created using MetaLocator's Legacy Interface Editor. Login to MetaLocator, click Interfaces, then edit, and expand the Legacy Settings group. Set Use SSL? to Yes, and click Save. Clear your browser cache, and then your connection issues should be resolved.
You may need to clear your browser cache to ensure you're seeing the latest.