How to Create a Local Area Network (LAN) Count the number of computers you need to hardwire. When setting up a LAN, you'll need to know how many computers will be connecting to the network via Ethernet. This will determine the number of ports you'll need. If you have four or less computers that you need to hardwired, you'll just need a router. If you have more than four, you'll likely need to get a switch to extend the number of ports available on your router.