Thanks for all the suggestions and input. Buried Ethernet isn’t practical here and would be cost prohibitive but it probably has the best capability. I will try the idea of using multiple nodes. I’m also going to check into Ubiquiti and Amplifi to continue my explorations in a field in which I probably qualify as sub moron meets old fart.
At Christmas, I bought my son a Netgear Orbi Mini 2-Pack AC2200 Tri-Band WiFi System from Costco. They are on sale for $170.00 for the main unit and one extension. For some reason, this setup has a better rating at Costco (4.7 stars) than the larger more expensive NETGEAR Orbi AC3000 Tri-band Wi-Fi System 3-Pack (4.2 star) which goes for $319.00. I got the 2-pack version of the AC3000 recommended by the Wirecutter at Best Buy and it has been reliable. However there definitely seem to be lemons or problems with any router, mesh or otherwise – my router hunt never turned up a router without some 1-star rants. So I bought my son’s router at Costco with the idea that we can return it if he isn’t happy with it. He is a robotics engineer, so it was nervy of me to give him a router for Christmas, but so far, he is happy with it.
Costco also sells an Add-On Orbi Outdoor WiFi AC3000 Satellite (4.5 stars) which might help for people with back houses. Costco also carries two Linksys Velop systems, a 3-pack Model AC4600 for $199 (3.6 stars) currently out of stock and a 4-pack Model AC2200 for $499 (4.2 stars).
Best Buy gave me 14 days to return my Orbi. At Costco, some electronics have to be returned within 90 days, but the mesh routers do not seem to be on that 90-day list, meaning that I seem to have an undetermined amount of time to return my son’s Orbi if necessary. (No, I do not own Costco stock. )