Updating the home WiFi lan

So I have been updating my home Wi-Fi network. It's been interesting.I have internet service from Time Warner/Spectrum/Charter and so the first step was to update to a faster speed. That was a $20.00 a month hit but I also had to update the modem.I had just updated the modem when we had the big lighting storm just a while ago and of course the new modem was one of the casualties. I had gone back to the Spectrum modem but it would not work at the higher speeds so add in yet another new modem. Quick BestBuy run though and that was solved. Then call Spectrum to activate the yet again new modem and they could activate the higher speed link.Next it was update the internal LAN to handle IPV6 and WiFi 6 and the network cards and adapters. For the network I chose to switch to a full mesh system from TP-Link; their Deco X20 which is a pretty much basic modern system, not the fastest or mostest but pretty solid and reliable. It also will handle WiFi 6 as it gets rolled out so should be good for a year or three.After the normal birthing pains thing seemed to settle down and the next step was to make sure all of the IoT things like lights and cameras and garage door still worked and surprisingly most worked right away and a simple turn off and on solved all of the light bulb issues.Several of the computers needed tweaks or replacement of the network card or adapter but after a day or three all but one machine was seeing download speeds between 150 and 200 Mbs and upload speeds north of 20 Mbs. The one that is still sluggish is an OLD HP Laptop that began life around when Windows 7 first came out with a network card that is at least two generations back and I'm not sure I will be able to do much more with it.Coverage now is uniform all over the house and the speeds to misquote Harry's father, "they are feeling MUCH better now".

When a friend moved to a new house, her son-in-law set her up with Wifi and cutting the cord with for her TVs. I forget what they're called and I think he had gotten them from CostCo, but there are three Wifi hot spots throughout the house, including in the casita where I stayed. I thought that the one in the casita was an Alexa, but it kept ignoring me when I tried to speak to it.
My own Wifi is mostly line-of-sight (my wireless router is under the TV which I can see from my dining table where my computer is set up) and a tablet I keep upstairs can connect. But I've heard of houses with dead zones (eg, behind a brick wall) where they had to set up extra wireless access points (WAP).
A fellow student in my UNIX/networking classes was divorced and he had applied what we were learning in class to set up a LAN involving several PCs and lots of cabling (that was two decades ago). Despite having been divorced since then, I've not been motivated to do anything elaborate -- I just want everything to work -- plus I tend to view a lot of the IoT as a "gaping security hole" (I have the source code for netcat and I'm pretty sure that it has a #define called GAPING_SECURITY_HOLE -- the code for doing sockets (ie, networking) is surprisingly small).
My current travail is my desktop. It was only about 11 years old, so when it died I took it to a repair shop recommended by my sister where they sold me a rebuilt with a solid-state drive and they transferred everything from the old hard drive so it was basically a pin-compatible replacement. After a couple months, that new drive crashed, so they replaced it and "repopulated" it with my old drive. OK, the data appears to be there, mostly, but all my tools are gone! MS Office, gone! No compilers, no FTP client, all my accounting (Quicken), my file comparer/transfer (BeyondCompare), my text editor. All support for my printer and my scanner. All gone! I can't even find any way to correct the time display to 24-hour. It's like I handed them my computer and they gave me back a big brick that I couldn't do anything with. I'm taking it back in this morning.
Hardware-wise, my old desktop had Wifi built in, but not the rebuilt so they added a USB dongle which worked. Now the "repaired" computer has no clue that it has Wifi, so that's another thing that needs to be repaired. I could use a CAT-5 cable, but that's 25 feet away plus it would be a definite trip hazard.
In one programming team I was on, we did a lot of quoting. One was from "Cheers", a play on an old standard male complaint about women, but we applied it to computers: "Computers! Can't live with them, ... pass the beernuts."

Since you mentioned Office and Quicken I'm going to assume it was a Windows machine - if not don't bother reading on.So if it was a Windows machine you can't say "only about 11 years old". In Windows machine years with manufacturers like Dell and HP that might be about 130 years old. It's amazing it lasted as long as it did.You say the repair shop sold you a "rebuilt" (is that a synonym for some other used machine that they repaired?) that after they transferred everything from your old hard drive to a solid-state drive worked like a "pin-compatible replacement." That seems like some pretty amazing magic. Your installed applications should not have worked on the "rebuilt". What did they do that made it unnecessary to reinstall them?Then the solid state drive died, so they replaced it and again transferred everything over from your old hard drive, only this time you used the word "repopulated." Is that significant, or is "repopulated" just a synonym for transferring everything over? I think you're saying that they tried to set up the replacement solid state disk the same way as the first one, but they somehow failed to do so.Hopefully when you bring it back they can pull off the same magic they did before.But unless keeping old stuff going is a sort of hobby or lifestyle, I'd recommend that you stop messing around and buy all new stuff. You might even consider going to Mac, whose OS is built on a version of Unix System V. When you bring up a terminal window on a Mac you get Unix. If you wait for the new Macbook Pro 16 that will likely be announced next month and get a mesh router for full coverage of your house (and upgrade your modem if appropriate) it'll set you back about $3500. MS Office (now Microsoft 365) and Quicken run on Macs. With a laptop you'll no longer have to sit at your dining room table but can sit in your living room with your screen displayed on the TV (using Bluetooth, unless your TV is also old).--Percy