[SalesForce] SFDX: Authorize an Org failed

You don't "need" the Connected App ordinarily, as it usually uses the Global Connected App that Salesforce uses by default. If you're having problems, all the usual software needs to be checked. Your firewall should allow access to localhost:1717, your computer should have a free port at 1717 (meaning, only one copy of the command line should be running at once), you should update your command line to the latest version via sfdx update, or as a final resort, try reinstalling the command line. You might also need the assistance of IT if your firewall, antivirus, or some other configuration is blocking access to localhost.

The VSCode extension from salesforce uses Salesforce CLI under the hood to manage the authorization .

CLI provides ability for you to authorize as many as orgs you would like with an option to set default org at the project level and also you can set default globally if you would like .

Below are some key points to understand

1. Your project directory has hidden directory .sfdx with a file sfdx-config.json.This file holds the default username .

2. You can also find a similar folder in your Operating system HOME directory that holds few more files . It will have file for every org you logged in json format with access token and refresh tokens to manage auth .

Now when you say you authorized it without alias thats not good practice .I would recommend when you authorize your org set a unique alias for each org and also select one of them as default alias .

Your vscode editor will show you default alias in the footer ,(you can even click and log into the org from there )

Salesforce is building capability to allow you to switch between orgs easily that will make life simpler .You can switch today easily by running sfdx force:config:set defaultusername=<alias> in terminal .

Always make sure to set a defaultusername for your project so that way you know which org your local project saves and retrieves files .