Have you verified there aren't issues along your route to the servers? Not on your end, or your ISP's localized segments (where they usually look when you call in)...but along the path you take to the server--between your location and Ormuco (SE's ISP).
I haven't, but since this problem has been going on for months (nearly a year) and affects only this single Internet activity, it's unlikely to be a routing problem. It certainly wouldn't be any kind of outage, as it would have to have been out for a protracted period of time and the network infrastructure of North America is simply not THAT awful (it's pretty awful, but that's pushing it).