This error happens when you're unable to find a route to host, and usually has something to do with your ISP or computers DNS cache. If you get this issue you can either wait it out, or use one of the following to try to fix it:
Use Google DNS (best method): Get Started | Public DNS | Google Developers
Flush your DNS Cache (may not work): How to clear the DNS Cache on a computer and web browsers?
Use Google DNS (best method): Get Started | Public DNS | Google Developers
Flush your DNS Cache (may not work): How to clear the DNS Cache on a computer and web browsers?