Excellent @ouroumov and @Bill_MI suggestions,
If you change your DNS (Google, OpenDNS) in the network settings you can get access?
I once had a problem located with an unavailable site, found checking through the commands:
- traceroute [ip/web-site url]
- mtr [ip/web-site url]
Checking the route and Ping can be helpful in case it was a problem in my ISP. As soon as I found out they corrected a problem with the route. And I didn't even imagine it could be that hehe
