Interested to learn how the “software still wouldn’t install” failure presented itself, exactly.
It’s quite common on my setup to choose the package, click the install button, see everything dim out for five seconds or so while nothing else happens, then the dim goes away; you then select the router again, hit install again, the dim happens again, etc. Is this what you were seeing?
I have found the solution to this is to quit and relaunch netinstall, choose “previous install” as quickly as possible, then the install button, then you will get the “formatting disk” message and everything will work. I have found that when I am able to use “previous install,” the hang almost never occurs, whereas if I have to select different packages, the hang occurs more than half the time; also, the longer it takes me before I hit the install button, the more the chance of the hang increases.
This has been happening to me for years, and I just live with it. I will have to try your solution of running in W7 compatibility mode and see if the problem goes away.