How many
mesh wifi nodes?

Usually two: the router where it already is and one node at the end with the worst coverage. If the flat is long and narrow, with a long corridor and two or three solid-brick load-bearing walls in between, you may need a third to cover the far end of the corridor or an isolated room. Typically an open-plan flat of up to 90 square metres is sorted with one or two, and only one with a corridor and thick walls goes up to three. The opposite mistake is more common than you'd think: fitting three or four nodes because the flat looks big on the floor plan, when what was really missing was two well-placed ones. More than three nodes in an ordinary home almost always means they're badly positioned, competing for the same airspace instead of sharing out coverage. Before adding another node, check whether the second one is at mid-height and halfway along, not hidden in a cupboard.

One per floor as a starting point, counting the floor the router is on: in a three-storey house, three nodes, lined up vertically so the signal crosses one floor slab rather than a slab plus two walls diagonally. If there's a basement or a garage separate from the rest of the house, count it separately rather than as just another floor, because the slab separating it attenuates far more than an interior partition and it needs its own point. If you also want to cover the garden or pool, that's another point specifically for outdoors, not an indoor node pointed outwards, which spreads the signal badly and leaves the inside worse served. In three-storey houses or ones with a basement it isn't unusual to end up with four nodes, but it's best to start with the minimum and add only where the signal genuinely fails, not for every room that looks far from the router on the plan.

No. A classic repeater picks up the router's signal and rebroadcasts it under a different network name, so devices don't switch points by themselves: you have to disconnect manually, and a good chunk of speed is lost on each hop. A mesh system keeps a single network name across all nodes, and the network itself decides at any moment which point to connect you through as you move around, without you noticing the switch. For a single area with poor coverage, a repeater may be enough and is cheaper. But as soon as there's more than one spot to cover, or people moving around the house with phones or laptops, mesh avoids the classic repeater problem: staying stuck to the distant, slow node because the device won't switch networks on its own. It's the difference between a network that decides for you and one you have to manage by hand every time.

Much better, yes. When a node talks to the router by cable instead of over the air, it stops spending part of its wifi capacity communicating with itself, and all the bandwidth available at that node is freed up for your devices. Over wifi, each hop between nodes costs speed; with two or three nodes chained wirelessly, the last one can end up well below what reaches the first. So whenever there's conduit, trunking or a network socket near where the second node goes, we recommend it without hesitation, even if it means running an extra length of cable. You don't need to cable every node: it's enough for the furthest one, or the one carrying the most load, to have that wired link back to the router. During a renovation or a new build is the time to plan in that cabling, because adding it later means chasing walls or visible trunking.

Because the provider is only responsible up to the router: from there inwards, the installation is yours, and 1 Gb fibre with badly distributed wifi feels exactly as slow as a weak line. The bottleneck is almost never the line you pay for, but how many obstacles there are between the router and where you use your phone or laptop, and whether the node meant to cover that area is well placed. It's easy to check: plug a laptop into the router by cable and measure the speed; if you get the speed you pay for there, the problem isn't the provider, it's distribution inside the home. Paying for more speed in that case changes nothing, because the limit isn't how much comes into the router but how much gets distributed well from there. Before upgrading your plan, it's worth reviewing where the nodes are placed.

On the floor, because the signal spreads worse from there than from a piece of furniture at mid-height. Inside a closed cabinet, behind the TV or in a drawer, because metal and the screen block much of the signal, and those are spots people choose for looks, not coverage. Right next to the boiler or the fuse box, because they generate electrical noise that causes dropouts that seem random and are hard to diagnose. And never at the exact spot where there's no coverage: that's the most common mistake of all. The node doesn't go where the signal fails, it goes halfway, where the signal from the previous node still arrives well, because a node placed in the dead zone receives poorly and therefore distributes worse than the router does alone. If you're torn between two locations, always choose the more open and visible one, even if it looks less tidy.

No. Past the right point, nodes start getting in each other's way: they compete for the same airspace, signals overlap, and instead of adding coverage the network loses efficiency constantly deciding which node to connect each device through. It's quite common for an installation to improve by removing a surplus node and repositioning the other two properly, rather than adding a fourth. This happens especially when all the nodes were bought in one go without first measuring where coverage actually failed, and were placed by instinct or one per room instead of according to where the real obstacles were. The practical rule is to add a node for each area the previous one doesn't cover, then test without the last one: if coverage doesn't get worse, it wasn't needed. Buying too many doesn't just cost money; it also complicates the network and can worsen the very result you were trying to improve.

For a small shop or office, yes: two nodes, one in the customer area and one in the back room, are usually enough, just as in a home. For a warehouse or a large workshop it's usually not the right tool, because domestic mesh is designed for a limited number of devices connected at once and for spaces with rooms, not open-plan warehouses with metal machinery interfering with the signal. What's called for there is professional access points cabled with PoE, which receive power and data over the same network cable, handle many more simultaneous devices than a domestic mesh node, and let you control and adjust coverage independently by zone. They also make it easy to separate the office, production and guest networks, something a consumer mesh system isn't designed to manage reliably in a high-traffic environment.