I use Mozilla Firefox at work and home. But it stopped loading websites at 1.10pm Wed 28th Jan 2016, after an auto update to v44.0.
Here is how I fixed it..
Interestingly a tell tale sign was that I could still load intranet and local websites – but nothing beyond the local network. nada – zip..
After a couple of hours, my work installation started working again.
I had rebooted the computer a couple of times, which didn’t seem to help immediately, but when it did suddenly start working, I ignored the problem as a one off glitch – at least until I got home that night and discovered the same issue!
I figured I needed to work out why this was happening on my Home install, as other employees in our business, and indeed many people in general may have this issue.
A quick Google hop to the Mozilla support pages showed that Windows Firewall *may* be causing the issue.
So I loaded Microsoft Firewall (using these Mozilla and Microsoft Firewall instructions) and it quickly became obvious that the issue has stemmed from Mozilla changing the Name of their software from Firefox, to ‘Firefox’ (with the single quotes) which has made the previous security setting fail.
Open windows firewall and change your settings as shown in these 2 screen captures.
So – Setting both Firewall instances to have access to the external network, solved the problem.
Hope that helps!