How to read your modem & router lights

May 01, 2011 7:00 AM by Laura Williams, M.S.Ed.

Posted in Living / Technology / Gadgets, Electronics & Automotive

Make Sense
Of Flashing LEDs

Let’s face it -- experiencing an internet outage can be frustrating, especially if you don’t know what’s causing the problem. Instead of staring at all those blinking modem and router lights with confusion, learn how to interpret the problem and get your service up and running as quickly as possible.

Modems and routers – The basics

If you subscribe to a cable or DSL internet service, your modem will act as a bridge to connect your cable service directly to your computer or your wireless router.

Your router, on the other hand, works to connect one computer network to another. The most common router for the casual consumer is the wireless router. The wireless router basically functions as a connection point to transmit your wired computer network to your wireless network.

All modems and routers have a series of lights that are designed to provide you with information regarding your internet connection. While most brands provide lights for similar purposes, every device will have a slightly different lighting configuration.

When your internet is working properly, take a minute to jot down exactly what your modem and router lights are doing. Write down the color of the lights, whether or not they're flashing, how fast they're flashing and if any of the lights are off. With this information on hand, the instant your internet stops working, you'll be able to tell if there's something amiss that the router or modem is trying to communicate. When writing this information down, make sure you check the back of the device as well to see if there are lights that display in the back.

Understanding the lights

Whether you're using a modem, a router or a combination of the two, the lights will provide you with certain information regarding your internet connection. Most devices will communicate the following information, although it's important to check your user manual to verify how the lights are supposed to display on your device:

Power -- the power light simply lets you know that the modem or router is plugged into a power source. When working properly, your power light should display a steady light.
PC (USB or eNet) -- In addition to a power source, your modem needs to be connected to a PC or a wireless router to be able to transmit data. Similarly, your wireless router needs to be connected to a modem. The PC light will remain on and steady when this connection is established.
Receive & send (Sync) -- These lights will flash as the modem or router tries to lock into an internet source or frequency. When a viable frequency has been found, the light or lights will usually stop flashing and remain on.
Online (Ready) -- After confirming upstream and downstream frequencies, the online light will begin to flash as the modem acquires an IP address. When this occurs, you're officially online. Depending on your device, the light may emit a steady or flashing light when working properly.
Activity (Data) -- The activity light will flash as your network sends or receives data.

If you have different lights than the ones listed here, make sure you consult with your manual or an online resource to confirm their purpose.