For those experiencing connectivity issues, try a different ISP/network. For example, I can't connect to any of the above networks via my regular Time Warner cable connection or via my T-Mobile hotspot. But I can connect via my Verizon hotspot.
Internet Issues in the US - Possible Backbone Issue
#1There seems to be an issue with Level 3 at the moment which is causing all sorts of sites to be unreachable for some people but not others. Rackspace (mail, hosting, cloud, etc), Facebook, Hotmail, Github, Digital Ocean, etc.