I would like to expand and say that the issue started a long while ago and I've just gotten fed up with it since it doesn't allow my PC to install anything even through applications that draw from github. However it's only my Desktop that this affects on my Wifi, all my other devices can access Github perfectly fine.

What is your dns setup on the computer, browser, and router? Have you tried with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf Did you clear your browser cache? https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox Are you running any security software besides MS Defender? Windows home or pro? You can also boot windows in safe mode with networking to test.

My DNS settings for my computer are 8.8.8.8, I assume that's what you're asking. And I shouldn't have any other security software running

I tried the rest of what you recommended and none of them fixed the issue, would my best option here be to try and contact GitHub support directly via a different device?

This is not a Github issue. They will tell you try another browser. Just for S&Gs, try changing all your DNS to 1.1.1.1, clear browser cache and dns cache(ipconfdig /flushdns from cmd line)and see what happens.