I've had this problem with a number of websites, inc APUG, and it seems often to be routing problems rather than the sites themselves.
In a previous case I raised an issue of a website not being available and David Goldfarb could access it whereas I couldn't.
In my experience, if it is a routing problem (DNS, etc) then you usually get one of the canned messages from your browser or it shows you the HTML error code. In this instance, I got a blank page (served it seems by the the Formulary's service provider) with just "Service Unavailable" in large type. So that looks to me like a problem at the source and not in the stream.