Building a computer network in your large home with two storey building is more difficult compared with a home with only one floor building and is sometimes frustrating. Thick concrete building generally contributes signal attenuation and dead spots in wireless. Running network cable is a hard work. But Powerline Ethernet adapter helps you build the network easily.
Should you build a home computer network from the scratch which consist of first floor where your Cable / DSL internet connection starts and the second floor where you would like to Expand the network wirelessly, you should assess your requirements to meet your needs. On the first floor, how many computers you need, how you connect them wired or wireless. On the second floor, this is important because you need to connect the first floor to the second floor where a thick concrete building will be an obstacle whether you run the network cable or wireless access.
In the first floor where your router gateway (with 4x Ethernet ports) is located connects two desktop computers which are close each other with the gateway router a wired connection for each of the computer is easier. You just need to run a network UTP cable from each of the desktop computer to the router Ethernet ports.
Now the challenge is how to connect several laptops with Wi-Fi enabled and other Ethernet based devices in the second floor to allow them connect and access the Internet? You have two options you run a network cable from the first floor to the second floor, or you provide wireless access from the first floor to the second floor clients. To run a network cable from the first floor to the second floor you need an extra effort probably by drilling the hole or run the clutter of the wires that will just look untidy.