A client has a large house with WiFi dead spots (lots of walls and thick floors). It is pre-wired with Ethernet. I've setup access points to the best locations I could find with Ethernet jacks. Even less than 30 feet away speeds are horrible because those walls block the signals so well. Most of the Ethernet lines are in the home office. Only a few run throughout the house and they are old CAT 5 cables anyways. Limiting them to 100 Mb/s. It's a 24 port switch but only about 15 lines are being used. It was just the cheapest switch larger than 8 ports Microcenter had in stock.
While I've tried to dissuade him. He's all hopped up about Mesh. I'm seeing if there's something I can still work on remotely. Before making recommendations on that or Powerline WiFi.
My preference is for Powerline WiFi. I'm not convinced Mesh will do the job. My preferred kit the TP-Link WPA-8630 Kit is getting hard to find. What with Amazon shutting down non-essential sales. The only replacement TP-Link seems to have is the lesser WPA-7510. I like the WPA-8630 as it uses 2x2 MIMO over the powerlines to communicate between devices. So, far it is the only one I've found to be reliable. Thus my reluctance to try another powerline system.
Also the Powerline run from the office to the basement to the kitchen is quite long. Those Powerline systems degrade quite a bit over distance.