AirPlay from Mac not working due to IPv6 configuration issue

This is not so much a question as the answer to something which I took a long time to sort out, and where the answer interested me. I have in my house three Macos machines updated to very latest Tahoe Software. I noticed that one of them, my "main" machine, although it had an Apple HomePod sitting next to it, would not "see" it in Airplay. I reset the Homepod and did/tested all the various things which the internet seemed to recommend. Nothing worked. I got the message that the Mac would not communicate with the Homepod (or with anything else on Airplay). Finally I compared the Network Settings of the "main" Mac with one of the other machines which did Airplay to the 'Pod. The answer, now verified, is that in "Settings - Network - WIFI - (my network) - Details - TCP/IP" the setting "Configure IPv6" had been switched off. Setting it to "Link-Local Only" meant that the machine communicated over Airplay. I did not switch off IPv6 by the way!!

Has anyone else seen this?

[Re-Titled by Moderator]

Original Title: Airplay from Mac