There are often problems on that domain. Maybe worse after an update so it's getting a lot of hits. The problem is always transient. Keep trying and you'll get through.
All of those work fine with the latest release. You probably just needed to do a Reset Updates after installation.
GHS isn't dead. Never was.
... however, the GHS repository is sometimes unresponsive. In my experience it always reappears within an hour or so (I think this is just local network / ISP issues).
Seems kind of random. Sometimes new installs don't handle Repository updates quite right. The most common failure seems to be going through the update process with apparent success, but some of the processes or scripts not showing up in menus.
Works fine for me. Pings go through, and I get the expected 404 error when I access the repository through my browser. The homepage comes up in my browser without problems. Where are you located? Maybe a network routing problem of some kind.
There have always been connectivity issues with that site. Maybe worse for some people than others, but always transient. Pretty certainly nothing to do with changes in PI after updates, though. It just gets noticed then because so many people are accessing the site then. But people report (and I've personally seen) connectivity issues pop up during routine automated updates, too. Until Mike is able to work out what his hosting service is doing wrong (and I think there's a good chance that's where the problem lies) the only solution is a bit of patience.
