How to Wire Your Computers into a LAN to Connect to the Internet

By John R. Levine, Margaret Levine Young

After you have the internet router set up, if you want to create a wired LAN, you need wires. (Okay, you already knew that.) Specifically, LANs use Cat 5 Ethernet cable with RJ-45 connectors — it looks the same as the cable you use to connect your router to your modem.

Cat 5 cables are available at any office supply store, electrical supply store, computer store, or even the occasional drugstore or supermarket, and you can find them in varying lengths, from 3 feet to 50 feet or more. You need one cable to run from the router to each computer. It doesn’t hurt to use a longer cable than you need, but it looks messy.

For every computer, plug one end of a Cat 5 cable into the computer’s network adapter jack. Plug the other end of the cable into the router.

After your computers are connected to the router and, indirectly, to each other, tell every computer about the LAN. Windows 8, 7, and Vista make it easy — as soon as you plug in your network cable, Windows contacts the router and sets up your connection. (The most common problem: The cable isn’t plugged in all the way at one end or the other.)

If your computer doesn’t connect automatically, try these steps in Windows 8.1:

  1. Open the Charms bar and click Search.

  2. Enter network in the Search box.

  3. Choose Network and Sharing Center to see which networks Windows thinks you’re connected to.

  4. Click Troubleshoot Problems.

    Clicking this option usually walks you through the solution.

In Windows 7, try this:

  1. Choose Start→Computer→Network.

    You see a window showing the computers and networks that Windows thinks you’re connected to.

  2. Click Network and Sharing Center.

    You see this window.

    The Network and Sharing Center in Windows.

  3. Click Set Up a New Connection or Network if this is the first time, or Connect to a Network to connect to a network that already exists (such as someone else’s LAN).

In Windows Vista, try this:

  1. Choose Start→Network.

  2. Click Network and Sharing Center.

  3. Click the Diagnose and Repair link to help fix the most common problems.

If you connect a Mac to your LAN, it can probably see the LAN and work without your lifting a finger as soon as you connect the cable. If you want (or need) to configure your network connection, try this:

  1. Choose System Preferences from the Apple menu and click Network.

    You see the Network window. Either the Ethernet or USB Ethernet entry should have a green light to indicate that a cable of that type is connected.

    Network window on a Mac computer.

  2. Click the Ethernet or USB Ethernet entry (whichever has the green light) to see the details of that connection.