If you’re doing any web development work, I hope you have a local development environment running on your computer, and that you aren’t FTP’ing your code to the server and then loading the page each time to see if your change works. (I’ve seen people do this, it’s painful, and slow). If you don’t have a local development environment setup, there are lots of options. WordPress developers, check out DesktopServer, VVV, or Local by Flywheel as great options for getting up and running with a local development environment quickly. When working with local development environments, you can typically only access your sites from localhost (your computer). Accessing your sites from another computer on the same network, or from elsewhere not the Internet, is not possible.
There are many reasons you may want to do get temporaryaccess to your local environment from the outside. I say temporary because your computer should not be used as a web server for many reasons including performance and security. In my experience temporary local access is handy mostly for testing scenarios, such as:
Testing your sites from mobile devices
Testing your REST API endpoints from