C4000 modem light guide

What does the status light ring on your C4000 modem tell you? Ver video below or see the descriptions for each light.

This guide applies to our C4000 modems (a round white device). If you have a black modem tower, go to our tower modem lights guide en su lugar.

This guide is for these models:
C4000BG   C4000BZ   C4000LG   C4000LZ   C4000XG

Vista de frente y de atrás del módem C4000

Video: C4000 modem lights guide

C4000 status lights overview

The C4000 series gateway modem was designed with a single light ring on the front, to simplify the process of checking the connection status. You'll have a DSL model (C4000BG, BZ, LG, or LZ) OR a fiber model (C4000XG), depending on your internet service. Regardless of the model, the LED ring on the front of the modem will work in the same way. If you have a DSL model, you will also see a luz de estado DSL en la parte trasera del módem.

Refer to the table for a quick summary of light colors. Or, see detailed descriptions of the modem lights below.

Light ring color Descripción
Blinking blue; solid blue Booting up; syncing with the network
Luz verde fija Conectado
Solid red Network failure; call or chat for help
Flickering green (fast) Sending or receiving data
Blinking green WPS trying to connect to a device
Blinking red WPS connection failed
Blinking amber-green or amber-white Updating firmware
Blinking green-red Network issue; call or chat for help
Apagada Not connected to the network

LED ring colors

The light ring or LED ring on the front of the modem shows you its connection status. When you first install the modem, you'll see different colors, and during normal everyday use, it will be green.

C4000 status LED ring

The light is AZUL

During initial configuración, the light ring will show the progress as it boots up and connects to our network.

  • The status light will blink blue as your modem searches for the CenturyLink network. 
  • It will turn solid blue once it has connected. 

The light is VERDE

A green light ring means you're online. Most of the time, your modem light will look like this.

C4000 showing green LED ring

The light is ÁMBAR

An amber or orange light ring means you need to complete online activation or your account has been temporarily suspended. Use the mobile app to complete setup, or contact us for more help.

C4000 showing amber LED ring

The light is ROJO

A red light ring means there's been a connection error. Prueba reiniciar el módem. If you still get a red light, you will need to chatea con un agente to get further troubleshooting help.

C4000 showing red LED ring

WPS pairing

La configuración protegida de WiFi (WPS) es una manera sencilla de conectar dispositivos a tu red WiFi. Simply push the WPS button on the modem, then select the correct network from your compatible device and it will connect without entering a password.

When pairing a device with your modem using WPS, you'll see the light ring change colors to let you know the connection status:


  • Blinking GREEN - Searching for a device and attempting to connect

  • Solid GREEN - The device is paired

  • Blinking RED - The attempted connection failed. Wait 2 minutes, then try again. Make sure you are selecting the correct network in your device's list of networks (the SSID printed on your modem sticker).


If the connection fails, the light ring will reset to solid green after 2 minutes. You can then press the button to try the connection again. Si la conexión falla en forma reiterada, reiniciar tu módem, después intenta nuevamente.

Actualizaciones de firmware

El firmware es el software integrado que controla tu módem. Las actualizaciones ocasionales son necesarias para agregar nuevas funciones y mantener el rendimiento del módem al máximo. When the firmware updates, you'll see the LED ring change colors to show its progress.


  • Blinking ORANGE and GREEN - An automatic firmware update is in progress. These typically run in the middle of the night and are prompted by our network. No necesitas hacer nada.

  • Blinking ORANGE and WHITE - You have prompted a firmware update through the admin settings and the upgrade is in progress. Typically you won't need to do this, as required updates run automatically.

Luz de DSL

The C4000LG and LZ models have a small DSL light on the back side, as shown in the photo. The C4000BG and BZ models have two DSL lights. This light will flash red and green while the modem is syncing with our network, at the same time the light ring on the front is blinking blue. 

Back of C4000LG showing DSL light

Once the modem finishes booting up and syncing, the DSL light will be green to confirm the connection to our network.


Note that the C4000XG does not have a DSL port or light.

DSL light color Descripción
Luz verde fija Connected to our network; line is active
Solid red Network connection error; call or chat for help
Apagada Nothing connected to DSL port

The DSL light is VERDE

A green DSL light means your modem is connected to our network and the line is active.

The DSL light is ROJO

A red DSL light means your modem is not connecting to our network, either because your service is not activated from the CenturyLink side, or because the jack is faulty. Si la luz DSL continúa roja después de verificar los cables y de haber probado con todos los tomas disponibles, tendrás que  chatear con un agente de servicio al cliente para obtener ayuda. 

The DSL light is APAGADA

Esto indica que no hay nada conectado al puerto del módem. Make sure the green DSL cable is firmly plugged in to the wall jack and the DSL port on the modem.

Solución a problemas de las luces de estado

If the main LED ring or DSL light on your C4000 indicates a problem based on the guides above, then there could be an issue with the network or with your equipment. Here are some things to try before reaching out for support:


  1. Reiniciar tu módem.

  2. Asegúrate de que tu equipment is plugged in correctly. If you have a DSL line (C4000BG, BZ, LG or LZ) and also have home phone service from CenturyLink, you need to place DSL filters on all landline phone cords in your home. No pongas un filtro en el cable del módem. Si tienes el C4000XG, no necesitas filtros para la línea.

  3. En algunos casos, la toma podría sufrir un desperfecto o, quizá, no estar conectada a la red de CenturyLink. Si tienes más de una toma telefónica en la casa, conecta el módem a una diferente y repite el proceso de configuración.

  4. In some cases, you may need to restablecer tu módem and complete setup again to fix severe connection errors. It's best to do this with guidance from a tech support agent.


Si el problema continúa, comunícate con nuestro departamento de asistencia técnica para recibir ayuda.

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