The configurations I've seen are trying to use some sort of Linux-based server or NAS, and a variety of clients including some on Windows.

FWIW, I've just been told elsewhere in the thread that what we've been trying using SSH should have worked out of the box as long as Hg and TortoiseHg were both installed (and, I assume though we didn't state this, as long as Hg is installed and properly reachable on the server side).

So, while I can confirm that the simple SSH access doesn't work reliably here right now, it is starting to sound like we've hit some unfortunate case that isn't necessarily Hg's fault. If so, I apologise if my comments were unfairly harsh, though I would still suggest that Hg would be more user-friendly if it could handle SSH connections itself without relying on additional software that must be installed separately.