For the past couple of weeks, I've not been able to use Stack Exchange because the CSS is not loading. On Meta it works fine since they use a static CSS, but on Stack Exchange, the CSS doesn't load. I've tried using Firefox, Chrome, and IE11; I've tried clearing the cache, rebooting and clearing the cache and then rebooting. None of this has worked. I found this question on Meta that mentioned checking that the CDN is not blocked, so I went and added it to the "Trusted Sites" in my internet options. I can now load the CSS in Chrome. But in Firefox and IE11 I still get the CSS not loading. I've tried navigating directly to a CSS that is supposed to load like this one and I get an error message.
This page can't be displayed
Turn on TLS 1.0, TLS 1.1, and TLS 1.2 in Advanced settings and try connecting to https://cdn.sstatic.net again. If this error persists, it is possible that this site uses an unsupported protocol or cipher suite such as RC4 (link for the details), which is not considered secure. Please contact your site administrator.
Secure Connection Failed
The connection to the server was reset while the page was loading.
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. Please contact the website owners to inform them of this problem.
Looking into these IE11 has the TLS 1.0,1.1,1.2 all enabled, so it's not that. I was wondering if there is anything that is not up-to-date with the CDN that Stack Exchange uses?
Firefox sends me to the Mozilla support site to check for answers. It basically says that there are methods of connection being used by the site that are not up-to-date and therefore not secure.
I cannot find a solution to this. It works fine in Chrome, but not in Firefox or IE11. According to the answer below there is nothing wrong or out of date with the CDN. So now I'm at a loss as to what the problem is. My co-work has the same problem, except that he cannot get it to work in Chrome either. I've checked the firewall and nothing stands out to me that could be causing this (and since this is a work computer there isn't much that I could do if there was anyhow). I have checked the Anti-Virus, and again I don't see anything that would prevent the CSS from loading. I know that this started sometime last week, I don't know the exact day. I have checked everything that I can think of to find the culprit. Is there anything else that might be causing this? I am using Win7 x64 with the latest browsers (all kept up to date).