Ii took time, but I kept scrupulously to your instructions, and I have now managed to access two of my still-being-maintained websites from other devices on my local network.(About 10 to go!)
There was a hitch with one of the sites. I only have 3 WordPress sites, and they are all 2021 sites, but I picked one of them for the test. Originally, I could only access the home page, and that without CSS or JavaScript. But I changed the NAME of the site, inside the WordPress settings in admin, to the IP address and the port, and it worked both on the computer with WampServer installed and on my LAN devices.
I only mention this in case someone else has a similar problem. And I should add the StackOverflow page with your advice for the same reason: [
stackoverflow.com]
Thank you for your help!