I'm looking for some advice. A relative of mine has moved in to a house where the standard broadband wifi router just doesn't work everywhere. In the past I have used TL-WPA7510 to get above 100MB wifi speeds. But in this situation I can't really use that because I don' want to have multple SSID's or have devices on the same SSID because in the past when I tried that the devices that connect seem to not seamlessly switch between strongest AP and sometimes stay connected to the weak signal AP. Instead I am looking for some sort of true mesh wifi network. I tried out the Amazon Eero pro but it's very disappointing. The wifi speeds drop dramitcally and I literally have to put loads of devices because it has to be able to talk to each other.

So instead of each device having to talk to the other over wifi, i'm looking for maybe a system like the tp-link powerlines that each device can talk to the network via powerline technology, meaning the devices don't have to be nearby. But what I am after is something that will allow me to have a single SSID for the entire house and my devices can smoothly switch to the strongest AP. Can anyone recommend any TP-Link system that may work in this way? I need something that can provide wifi speeds upto 300 to 400MBs

Thanks