Configure Firefox to allow restricted ports for InstantWP

InstantWP is a complete standalone, portable WordPress development environment. By default, Firefox might block the ports (above 10000) it uses. You'll see the following error message if this happens:

This address is restricted 
This address uses a network port which is normally used for purposes other than Web browsing. Firefox has canceled the request for your protection.

In order to resolve the issue, you need to:

1. In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful. 
2. Search for network.security.ports.banned.override
3. Open it (or create new, if it doesn’t exist), and insert 10080 (as string, not as number!) at the end.