Connect your ethernet cable to the router, not the modem

Your modem connects to the internet through your internet service provider's line (cable, fiber, or phone line). Your router takes that internet signal from the modem and broadcasts it to your devices. The ethernet cable from your modem plugs into the router's WAN port (or Internet port), and then separate ethernet cables from the router go to your computers, printers, or other devices that need a wired connection.

If you plug an ethernet cable directly into the modem instead of the router, only that one device gets internet. Everyone else in your home loses their connection. The modem is designed to receive one incoming signal and pass it along; the router is designed to split that signal among many devices at once.

Key Takeaways

  • The ethernet cable from your modem plugs into the WAN or Internet port on your router, not into one of the regular ethernet ports.
  • Once the modem connects to the router, you plug other devices into the router's regular ethernet ports (usually labeled 1, 2, 3, 4).
  • Plugging a device directly into the modem bypasses the router entirely and disconnects everyone else from the network.
  • Most routers have one WAN port (usually a different color) and multiple LAN ports for your devices.

Understanding the ports on your router

Your router has several ethernet ports on the back. One is labeled WAN, Internet, or sometimes shown in a different color (often blue or yellow). This is where the cable from your modem goes. The other ports are labeled LAN (Local Area Network) or straightforward numbered 1, 2, 3, 4. These are where you plug in your computer, printer, gaming console, or any other device in your home.

The WAN port is special because it's designed to receive internet from outside your home. The LAN ports are designed to share that internet with devices inside your home. If you accidentally plug your modem into a LAN port instead of the WAN port, your router may not recognize the internet signal at all, and nothing will work.

What happens if you skip the router

Some people wonder if they can just plug their computer directly into the modem and skip the router altogether. You can do this, and your computer will get internet. However, only that one computer gets online. Your phone, tablet, smart TV, and any other device cannot connect because the modem has no way to split the signal.

Additionally, connecting directly to the modem removes the router's built-in firewall, which adds a layer of security between your devices and the internet. The router acts as a barrier that filters out many unwanted connections before they reach your computer.

Setting up the cable path correctly

The correct path is: Internet line (from your ISP) → Modem → Router WAN port → Router LAN ports → Your devices. Start by plugging your modem's power cable in and waiting for the lights to stabilize (usually 2 to 3 minutes). Then take an ethernet cable and plug one end into the modem's ethernet port and the other end into your router's WAN port.

Next, plug your router's power cable in and wait another 2 to 3 minutes for it to fully start up. Once both devices are ready, you can plug ethernet cables from the router's LAN ports into your devices. If you're using WiFi instead, you don't need ethernet cables for those devices—they'll connect wirelessly to the router.

Identifying which port is which

If you're unsure which port is the WAN port, check the labels on the back of your router. The WAN port is usually marked clearly and is often a different color from the LAN ports. If the labels are worn off or hard to read, check your router's manual (usually available as a PDF on the manufacturer's website) or look at the diagram printed on the router itself.

Most modern routers have the WAN port on the far left or far right, separate from the numbered LAN ports. Some routers also have a small diagram showing which port is which. When in doubt, the port that looks different or is labeled separately is almost always the WAN port.

Troubleshooting a wrong connection

If you plugged your modem cable into a LAN port by mistake, your internet won't work. The fix is straightforward: unplug the ethernet cable from whichever LAN port it's in and move it to the WAN port. Wait about 30 seconds for the router to recognize the new connection, and your internet should come back online.

If you plugged a device directly into the modem instead of the router, that device will have internet but the rest of your home won't. Move the cable to one of the router's LAN ports, and the other devices will reconnect. If they don't reconnect right away, restart your router by unplugging it for 10 seconds and plugging it back in.

When you might want a direct modem connection

In rare cases, you might temporarily plug a computer directly into the modem for troubleshooting. If your internet is down and you want to test whether the problem is with the modem or the router, connecting one device directly to the modem can help you figure that out. If the device gets internet when plugged into the modem but not when plugged into the router, the problem is with the router, not your ISP connection.

Once you've finished troubleshooting, plug everything back into the router so all your devices can use the internet again. Leaving a device plugged directly into the modem long-term means everyone else in your home loses their connection, so this should only be a temporary step.

Frequently Asked Questions

Can I use a really long ethernet cable from the modem to the router?

Yes. Ethernet cables work fine at distances up to 100 meters (about 330 feet), though most home setups use much shorter cables. If you need to run a cable across your house, a 50-foot or 100-foot cable works just as well as a short one. Just make sure it's plugged into the WAN port on the router, not a LAN port.

What if my router doesn't have a WAN port?

Some older or very basic routers may not have a clearly labeled WAN port. In that case, check the manual or the manufacturer's website for your specific model. Occasionally, one port is designated as WAN even if it's not labeled. If you truly cannot find a WAN port, the router may not be designed to work with a modem and might be a mesh system or access point instead.

Do I need an ethernet cable from the modem to the router if I'm using WiFi?

Yes. Even if all your devices connect to the router wirelessly, the modem still needs a wired ethernet connection to the router's WAN port. The modem and router must be physically connected by cable so the router can receive the internet signal from the modem and broadcast it wirelessly to your devices.

Can I plug multiple devices into the modem?

No. A modem typically has only one ethernet port. Even if it had more, the modem is not designed to handle multiple devices the way a router is. The modem's job is to receive one signal from your ISP and pass it to the router. The router's job is to split that signal among many devices.

What if I have two routers—where does the modem cable go?

The modem cable goes into the WAN port of your main router (the one connected to the modem). The second router can connect to the first router through a LAN port on the main router, or it can be set up as a wireless access point. Check the manual for your second router to see which setup it supports.