I’ve hooked up a router in the kitchen, wired to the router in the study, and connected the iMac and my Dell laptop to it. Unfortunately, while you can see files on the main computer from those computers, you cannot access them (so, for instance, HWMBO tried to play an mp3 file which he could see from the laptop. It gave him an error message. So it seems that adding the router has screwed up the networking and file sharing. Fuzzbuzz!
We’re going to Cardiff tomorrow for a short break, so I won’t be able to try to fix it until Sunday or Monday at the earliest.
Will post when we get back.