I use Windows 10 and for the last few days, I face a problem on some website few of them are moz.com, edx.org, coursera etc.
I face the similar problem on my laptop and desktop system which is connected by one Dlink router. I use wifi for laptop and wired connection from the wifi modem to the desktop.
I used mobile 4g internet to check the problematic website are working fine. Is it a router problem?
I did reset and reboot of router both did not help. Firewall checked it is normal.
Coursera, like many websites, uses a different domain to load resources such as the CSS stylesheets, in their case a CDN from Amazon. For coursera.org, viewing the page source reveals:
<link href="https://d3njjcbhbojbot.cloudfront.net/webapps/builds/front-page/app.ad4352e12e75c33c5276.css" rel="stylesheet">
For moz.com:
<link rel="stylesheet" href="https://d2eeipcrcdle6.cloudfront.net/assets/dist/styles/moz-b259826f.min.css">
Maybe cloudfront.net is having problems in your region, or is blocked somewhere:
Getting the resource directly (like d3njjcbhbojbot.cloudfront.net/...c5276.css) might show an error message.
Amazon's status page might help: https://status.aws.amazon.com/
If the problem shows in different browsers, then somehow your modem/router, virus scanner or even your provider might be blocking those.
If the direct link works, then some browser plugin that prohibits third-party content might be the culprit.
If the direct link does not work, maybe the settings of your DNS servers (either on the computers and/or in the router) got compromised by some malware. In that case you might have noticed some weird advertisements as well. See, for example:
You might see some indicator in your browser's location bar (for some browsers, look at the right, not at the left) or developer tools (for IE hit F12 to open those).
For the Coursera issue- This is a problem with the local ISP provider(BSNL) in India. They appear to be blocking all outbound traffic to domains like *.cloudfront.net.
The page fails to load its css and hence gets displayed incorrectly. Ask them to stop blocking or switch to an alternate ISP- have verified that the page loads correctly on others.
