Sorry for the delay in replying; had a sudden (and very welcome) rush of client work. Weirdly, it now is working in Chrome. Edge/IE always worked, FF worked, but I don't have Opera installed and forgot to check iOS Safari on my wife's iPad. But the unexplained part is that Chrome didn't work, and now it does. I had not turned off Norton Internet Security and was planning to do that just now, when I discovered there was no problem left to deal with, at least as far as Chrome is concerned. Perhaps NIS did its own heuristic analysis and opened the ports to Chrome. Dunno and don't know how to check anymore.
On the other hand, something new did happen, and I'll report that in a separate post.
Peter