Mesh Lab

The shop will sell you a mesh kit. The forum will tell you a £30 repeater is fine. Neither of them has seen your house. This takes the floor plan you already drew and simulates all three options on it — one router, router plus repeater, and a two-node mesh with a cable between the nodes — on one shared grid, so the coverage numbers can honestly be compared.

The difference between the last two columns is the cable. A wireless repeater hears the router and talks to you on the same radio, so it spends about half its airtime relaying and roughly halves the speed through it. A node with an Ethernet cable back to the router does not, and behaves like a second router. Estimates from a physics model, not measurements — and the second node’s position is chosen by search, so it does not know where your sockets are.