A handful of ways exist to set up a home network to share an Internet connection, but the safest, most reliable and scalable way is to use a router and switch or hub in combination. Placing the switch between the cable (or DSL) modem and the wireless router adds an extra layer of protection from threats on the Internet and adding more connections to the network is as simple as plugging another router into the switch.
Unplug the power supplies for the cable modem, switch and wireless router. Unplug any Ethernet cables that are plugged into any of them.
Connect an Ethernet cable to the Ethernet port on the back of the cable modem.
Plug the other end into a numbered Ethernet port on the switch. Do not plug the cable into a "LAN" or "Internet" port. If you are using a dedicated switch and not a converted router, any Ethernet port will do.
Connect another Ethernet cable to another numbered Ethernet port on the switch and plug the other end into the "WLAN," "WAN" or "Internet" port on the wireless router.
Plug the power supplies of the cable modem, switch and wireless router in. After two minutes, the network and Internet connection is ready to go.
Connect computers to this network by logging them into the wireless network, plugging them into the wireless router with an Ethernet cable or plugging them into the switch with an Ethernet cable. Computers on the wireless network may not be able to connect to computers on wired connections.
Most Ethernet routers can be placed in "switch" mode. If you have an old router sitting around, check its owner's manual for information on setting it up as a switch. Some automatically changes to switch mode when connected using the above process.