A simple router, not the modem. But very simple and inexpensive operation (14). Ethernet is connected to the outlet box and handles lock on the IP that provides it the box and to retrieve the DNS of your provider. And we can stop there. With a laptop, tablet or smartphone, we look WiFi network and returns the key to establish the connection. The network name and key are written in the router. The choice of channel is automatic and its IP is 192.168.1.1 gateway Of course, nothing prevents to enter its interface with a browser and change the settings (channel, key, network name, gateway address if several). I tested live on a linksys router LAN via a PLC from the same Linksys and live on a LAN Livebox. In any case it is wedged on the supplied IP. And I configured IP gateway 192.168.2.1 to avoid conflict with the Livebox. He will serve me to make WiFi in too far livebox dependency and on a different power grid preventing the CPL. Of course we had to take a LAN cable between two buildings. The range of WiFi is at least 10 m with cinderblock wall. So I suggest for such a need, especially in view of its price.
