As a developer you will run into various types of issues. Some of them are database connection related as you are trying to set up your local environments some are staging or live site.
Here is a quick way for you to test your connectionstring without having to open the Database.
1. Open a notepad.
2. Save as ConnectionTest.udl (make sure you select all type)
3. Close the document.
3. Right click on the file and select properties.
4. Select Provider tab and select your provider.
5. Click connection tab and select connection
Once you are done selecting all the fields , click “Test Connection” Button.
If it doesn’t succeed you have an issue. Fix it and move on.