I wonder if instead of fixing the OS directly, it'd be better to make the firewall changes in an Internet router and just send them the new one. You'd probably

I wonder if instead of fixing the OS directly, it'd be better to make the firewall changes in an Internet router and just send them the new one. You'd probably want to keep the existing router as well to avoid the need to login to find ISP settings (or avoid calling the ISP), but as long as the new router can be setup as a bridge to the existing one I see no reason why it couldn't work. The added advantage of doing this is that you can block all traffic associated with Microsoft's user tracking servers, which should work (as long as Microsoft don't switch the server name in use). Either that or recommend avoiding the Windows 10 upgrade. Windows 7 in particular should be sticking around for quite a while yet.