In a smaller, wooden house a single access point may provide good coverage for the entire building. Nice and easy. But if you have a multifloor brick and/or concrete construction, you are in for trouble. Many houses are built like bunkers: reinforced concrete floors and sturdy walls that kill all WiFi signals. You will need multiple access points per floor. For the access points you will need a wired distribution network. Wireless is only for the last hop to the device, the access point needs a wired feed. Unfortunately only 21st century houses tend to have high speed network cabling built in. In older buildings the distribution network is often the main challenge.
Using the power lines for networking is a popular alternative, if you search for solutions. Unfortunately the results are most often not even close to the expectations. This is easy to test. Just plug the powerline adapters to adjacent power sockets and test the throughput. It might be a measly 30 Mbps instead of the hundreds advertised on the box. With more distance the speed will drop even lower. If the sockets are in separate fuse circuits you need an electrician to bridge the circuits. But still you won’t get the throughput you need.
Another widely offered alternative is to use wireless for the distribution network. It is called Mesh WiFi, WiFi repeater or Wireless Distribution System (a.k.a. WDS). The inefficiency will cause problems because there will be so much wireless traffic going back and forth. The net effect is a slow network. In the best mesh access points there are two radios: one for the clients and one for the backhaul, but they tend to be pricey.
Most houses have telephone cables connecting the floors. In the best case the cabling is not used anymore at all. If the telephone cables are installed in tubes inside the walls, you can easily replace them with Ethernet cables. Every access point will need its own feed (cable), but there is not room for many cables in the tube. The professional solution is to put a network switch on every floor and run only one Ethernet cable between the floors. If you only need a couple of access points on a floor, you might get by using twin Ethernet cables. Actually, you can use a single Ethernet cable to transfer two 100 Mbps connections because only from gigabit up are all 8 wires used. With twin cables you can run 4 x 100 Mbps in a single tube. Is it reasonable to install 100 Mbps Ethernet today? In residential use it should be plenty for the next 10 years or so (unless you have fibre connection from the house). Even if the phone cables are installed on the surface, you may still use four wires to get speeds up to 100 Mbps. Either way, you can still use the old phone system to get a neat and inexpensive distribution network. If that is not possible, you need to run cables through ducts, a stairwell or on outer walls, increasing the amount of work to be done.
In every case the cabling job is best left to professionals. They have the tools to install and test the connections. Most electrical, telephone or data service shops do cabling. Ask for a couple of tenders and take your pick. Just make certain that all the cables will be tested and you get the report. A proper tester will cost well over a thousand Euros, so the handyman next door may not have one. All professionals do.
You will need multiple access points per floor to get good coverage through brick walls. Even if you can crank up an access point to cover the whole floor, the cell phone in the last room can’t reach back to the access point. With multiple access points the administration needs to be organized. Manually keeping just five access points in synch regarding all settings and updates is a chore. Ubiquiti has affordable access points and the central controller software is included. The Ruckus brand XClaim would be another alternative, but XClaim doesn’t seem to have a distributor in Finland at the time of writing.
The access points need power to operate. The neatest solution is to feed the power over the Ethernet (a.k.a. PoE). The network switch provides the power, so the switch needs to have a power supply big enough for all the access points. There are two standards for PoE: older 802.3af and later 802.3at (a.k.a. PoE+). Latest 802.11ac access points are power hungry and often require a PoE+ switch. Some vendors have their own, non-standard PoE solutions (often called “passive”). In that case it is best to stick with the same brand for access points and switches to ensure compatibility.