The basic connection: what goes where

A modem and router are two separate devices that work together. The modem connects to your internet service provider's network and receives the signal. The router takes that signal from the modem and broadcasts it wirelessly throughout your home so your devices can reach the internet. To connect them, you run a cable from the modem's output port directly into the router's input port — usually labeled WAN or Internet.

The physical connection is straightforward and takes less than a minute. After that, you may need to restart both devices so they recognize each other. Most of the time, once they are plugged in and restarted, they work automatically without any settings to adjust.

Key Takeaways

  • Connect an ethernet cable from the modem's output port to the router's WAN or Internet port — this is the only cable that matters for the connection itself.
  • Restart the modem first, wait for its lights to stabilize, then restart the router and wait for it to fully boot before testing your internet.
  • If your router has a setup screen when you first power it on, follow the prompts to name your network and create a password.
  • A working connection means your modem and router lights show steady green or blue — blinking is normal during startup, but should stop within two to three minutes.

Step 1: Locate the correct ports on both devices

On the back of your modem, you will see several ports. The one you need is usually labeled Ethernet Out, LAN, or sometimes just has an arrow pointing away from the device. On the back of your router, look for a port labeled WAN, Internet, or Uplink — this port is often a different color (usually blue or yellow) than the other ethernet ports on the router. The other ports on the router are for connecting your devices directly by cable; ignore those for now.

If you cannot find these labels because they are too small to read, check the manual that came with your device or search the manufacturer's website by model number. The model number is usually on a sticker on the back or bottom of the device.

Step 2: Connect the ethernet cable

Take a standard ethernet cable — the same type used to connect computers to routers — and plug one end firmly into the modem's output port. Push until you hear or feel a small click. Then plug the other end into the router's WAN or Internet port with the same firm pressure. The cable should sit flat and not be bent at sharp angles.

You do not need any other cables between the modem and router. Power cables go into wall outlets separately. If your router came with a cable already attached to one end, use that instead of a loose cable — it is the same thing, just pre-installed.

Step 3: Power on and restart in the right order

If both devices are already powered on, unplug the modem first and leave it unplugged for 30 seconds. Then plug it back in. Wait for the lights on the modem to stop blinking and show a steady green or blue light — this usually takes one to three minutes. This tells you the modem has connected to your internet service provider's network.

Once the modem lights are stable, unplug the router and wait 30 seconds. Plug it back in and wait for its lights to stabilize as well. This restart sequence ensures both devices recognize the connection between them. If you restart the router before the modem is ready, the router may not find the internet signal.

Step 4: Test the connection and set up your network name

Once both devices have stable lights, open a web browser on any device connected to your router's wireless network. Try visiting a website like google.com. If the page loads, your modem and router are connected correctly.

If this is your first time powering on the router, you may see a setup screen asking you to name your network and create a password. Follow those prompts. The network name (also called SSID) is what you will see when you search for WiFi on your phone or laptop. The password is what you will type to connect. If you do not see a setup screen, you can usually find these settings by typing your router's IP address into a browser — check your manual for the exact address, but it is often 192.168.1.1 or 192.168.0.1.

What the lights mean

Your modem and router will have several small lights on the front or back. During startup, these lights blink as the devices boot up and communicate. Blinking is normal and expected for the first few minutes. Once everything is connected, most lights should be steady green or blue.

A red light or a light that stays off usually means something is not connected properly. If you see a red light on the modem, the cable to your internet service provider may be loose, or the service itself may be down. If the router light is red or off, check that the ethernet cable between the modem and router is pushed in firmly at both ends. Unplug and replug the cable if you are not sure.

Troubleshooting if the connection does not work

If you followed the steps above and still have no internet, start by checking the cable itself. Ethernet cables can be damaged if they are bent too sharply or pinched under furniture. Try a different cable if you have one available. Make sure both ends are clicked in firmly — a loose connection is the most common reason this fails.

Next, check that you plugged into the correct ports. The WAN or Internet port on the router is not the same as the regular ethernet ports. If you plugged into the wrong port, the router will not receive the internet signal from the modem. Unplug and move the cable to the correct port, then restart both devices again.

If the modem light is red or off, the problem is between the modem and your internet service provider, not between the modem and router. Contact your service provider to check if there is an outage in your area or if your account has an issue.

Frequently Asked Questions

Do I need to use an ethernet cable, or can I connect wirelessly?

You must use an ethernet cable to connect the modem to the router. Modems do not have wireless capability — they only work with a wired connection. Once the router is connected to the modem by cable, the router broadcasts wireless signal to your devices.

What if my modem and router are in different rooms?

You can run an ethernet cable between them as long as it is not longer than 100 meters (about 330 feet). For most homes, a standard cable works fine. If the distance is very long, you may need a cable rated for longer runs, but this is rare in residential settings. Keep the cable away from power lines and do not coil it tightly, as this can cause interference.

Can I connect multiple devices to the modem directly instead of using a router?

Technically yes, but it is not practical. A modem usually has only one ethernet port, so you could connect only one device at a time. A router lets you connect many devices at once — both wirelessly and by cable. That is why routers exist.

Do I need to restart my modem and router every time I use the internet?

No. Once they are connected and working, you leave them plugged in and running all the time. They are designed to stay on continuously. You only restart them if something stops working or if your internet service provider asks you to troubleshoot.

What if my router does not have a WAN port?

Some older or very basic routers may not have a clearly labeled WAN port. In that case, check your router's manual to see which port is designated for the modem connection. If the manual is lost, search the manufacturer's website by model number. If the router truly has no separate input port for the modem, it may be a very old model and you may want to consider upgrading.