I don't think a Windows update would affect the Browser unless something was change on the ISP side. And if the Browser settings weren't change prior to this I would look at the O/S update.

Hi Terry, Could you try the solutions in the following article, and see if any of them help: Firefox can't load websites but other browsers can

Hi Chris My problem with firefox seemed to occur after I had a recent windows 10 features update. It worked perfectly well before that. I have run a comprehensive malware check with no issues reported. I turned off my virus software and reloaded the browser again with no effect. I checked that windows firewall was allowing firefox as an application. I have disabled IPv6 and prefetching again to no effect. When firefox is initially loaded and only has a single tab visible when I enter about:config the browser behaves as if its trying to connect to the internet (the black dot oscillates in the tab header). By opening other tabs I eventually get about:config to actually appear. I do not use a proxy.

Did you reset your router or reboot the router? And does other Browser work without issue?

Hi I have reset the router - to no avail. Other browsers work fine. I uninstalled firefox and reinstalled with a completely fresh version - no add ons etc. Still behaves the same way.

Hi Terry, Let's try refreshing Firefox. This will purge a lot of your Firefox files, while retaining most of your personal data. For instructions, check out the following article: Refresh Firefox - reset add-ons and settings

Hi Chris No joy I'm afraid. A clean fresh firefox behaves exactly the same.

Terrys72 said

Hi Chris No joy I'm afraid. A clean fresh firefox behaves exactly the same.

When you mean clean was that also deleting the Mozilla folder as well?

Hi I uninstalled firefox using IObit uninstaller pro - I believe the mozilla folder was removed. I then downloaded a fresh copy and executed that.

I've never heard of IObit uninstaller pro, so I choose to be skeptical of it. ☺️

Let's avoid using third-party applications.

1. In the Windows app settings panel, uninstall Firefox.
2. Reboot your PC.
3. If it exists, delete the folder "C:\Program Files\Mozilla Firefox\"
4. Install the latest version of Firefox using the instructions in the following article: How to install Firefox on Windows.

Hi Firefox is not listed as a windows app! The desktop shortcut reveals its location to be "C:\Users\Terry&Mo\AppData\Local\Mozilla Firefox\firefox.exe". Is this significant?

Hi I have removed this version using firefox's uninstaller. I have reinstalled firefox as per instructions - now at the expected location. No change - cannot access the internet.

Hi Actually mozilla crashed. I sent the crash report as requested.

Terrys72 said

Hi Firefox is not listed as a windows app! The desktop shortcut reveals its location to be "C:\Users\Terry&Mo\AppData\Local\Mozilla Firefox\firefox.exe". Is this significant?

That's definitely wrong! It should be in the in the Program Files folder. Are you sure your Windows account has permission to install Firefox?

Hi Please see my subsequent responses.

Does that mean the new installation has a desktop icon that is pointing to the proper location (in Program Files), and the problem still occurs?

There must some detail we're missing. As a test, instead of disabling your firewall and anti-virus, completely shut them down. If the problem goes away, then we'll look at the configuration to allow you to use them and Firefox together.

Hi Chris. I have turned off the firewall and my antivirus. The problem remains. Do you want me to uninstall my antivirus?

Hi Chris Forgot to confirm that firefox is now in its expected location!

Would you mind sending us a video of what you're seeing? For instructions, visit https://www.howtogeek.com/183231/how-to-record-your-desktop-and-create-a-screencast-on-windows/

Hi Chris Cannot use this software as I do not have the necessary hardware components. I have uploaded a screenshot if that helps.