laserlight Thanks for your response!
I'm very curious about mesh networks -- especially the claim of seamless traffic handling even as you move from hotspot to hotspot. Is there any way to emulate this seamlessness with a simple network consisting of two routers connected by an ethernet cable? My knowledge of network nomenclature is sorely lacking, but I think this topology would be described as a WiFi network with an extra Wireless Access Point (WAP).
i'm also wondering if a mesh network requires installation of any special networking protocol or updated hardware on client devices (computers, laptops, TVs, phones, tablets, gaming consoles, etc.). From the descriptions I've read, it doesn't sound like you do. Although I have seen reference to 802.11s.
You are correct that I need a simple solution for my family member. A salient illustration of the technical competency is the fact that they have a laptop they can't use because they forgot the password. I only just reinstalled the OS last Christmas after wiping the hard drive of all the sluggish cruft. Other concerns for the mesh network products you describe is cost. They all seem to start around $200-300 for any functioning system. For myself, I'm concerned about privacy. All of those products appear to have network-enabled features and phone app installations that suggest the vendors will be rifling through your phone and correlating network stats with your account in some nefarious data profiling operation.
I'm really curious about how I might improve my network to have a single network SSID and password that can effectively and quickly switch between hotspots. I've installed DD-WRT before, and have been very satisfied with the two-routers-connected-via-ethernet-cable-under-the-floor approach running in my apartment. It currently has two separate SSIDs but just one (bridged) network. The ethernet cable brings fast, reliable connectivity from my office (where the ISP line comes in) to the pile of TV devices (which are on the other end of the building). This approach requires basically no maintenance or configuration once configured and has been extremely stable thanks to linux-based firmware. Downsides are a) two differently named hotspots and b) a sort of dead space in the middle of my apartment, and c) devices often fail to switch to the nearer hotspot as we move about the apartment.
EDIT: I've been looking at the DD-WRT Linking Routers article. It's not especially well-written, but does attempt to clarify some of the concepts involved. It describes:
Access Point / Switch (connecting routers via ethernet cable)
I'm still digesting it, and it's a bit confusing. E.g., it doesn't really clarify differences between repeater and client topology, for instance. I'm still picking through the article and the white paper.