Yes, it disables access to remote resources: https://support.mozilla.org/en-US/questions/1263417 https://support.mozilla.org/en-US/questions/1263417 So if you

Yes, it disables access to remote resources: https://support.mozilla.org/en-US/questions/1263417 https://support.mozilla.org/en-US/questions/1263417 So if you have a local web server (like on localhost), you'll still be able to access it, but you won't be able to access non-local IPs.