How to read the lights on your tower modem

This guide applies to any tower or box-style CenturyLink modem/router.

top tower modems

For all following models:
Actiontec   *   Adtran   *   Calix   *   Technicolor   *   Zyxel 

Not the right kind of modem? Try the C4000 lights guide instead.

There's a lot of technology built into that black box that brings your internet connection into your home. Learn what the flickering lights on the front of your modem mean, and how to troubleshoot related problems with your connection. 

Diagram of modem with green power light

After the power cord is plugged into the back of the modem, the modem will start testing its own hardware and software. Once your power light turns solid GREEN, it is fully booted up. Check the DSL light next, or see the descriptions below if the power light is not green.


The power light will be OFF when the modem isn't plugged in or if it doesn't have a power source.

Power light off (gray)

The power light will turn RED while the modem is testing its own hardware. If it stays red after a few minutes, this can indicate hardware or sofware failure.

Power light red

The power light will turn AMBER/ORANGE or may BLINK GREEN and AMBER while the modem is testing its own software.

Power light amber (orange)
Power light flashing green and amber

Troubleshooting the power light

If the power light remains offredamber, or blinking for more than 30 seconds, there may be a problem. Here are some things you can try:

  1. Make sure you are using the correct power supply (the one that came with the modem).
  2. Try rebooting your modem by turning it off and unplugging it, waiting 30 seconds, then plugging it in and turning it back on.
  3. To prevent overheating, make sure your modem is in a place with good air circulation, 2 to 3 feet away from other devices that create heat.
  4. If you are using a power strip, surge protector, or you have a lot of devices using the same power source as your modem, it may not be getting sufficient power. Make sure it's plugged directly into a wall outlet, or try a different outlet.
  5. As a last resort, try resetting your modem to the default settings. 

 

If the problem persists, contact technical support for help.

Diagram of modem with green DSL light

After the phone cord is plugged into the back of the modem, and your equipment is set up correctly, the modem will start searching for a DSL signal. Once the DSL light turns solid GREEN, it is connected to the core network. Check the internet light next, or see the descriptions below if the DSL light is not green. 

Note: If your modem has two DSL lights, this simply means you have a "pair-bonded" connection, or two DSL lines put together to increase service speed. But the function of the two DSL lights is just the same as one.


The DSL light will be OFF if it doesn't detect a network connection. If it remains off for more than a minute after the power light turns green, see the troubleshooting instructions below.

DSL light is off (gray)

The DSL light will BLINK SLOWLY while searching for the CenturyLink network equipment. If it blinks for more than 5 minutes, see the troubleshooting instructions below.

DSL light blinking slowly green

The DSL light will BLINK QUICKLY when it detects the equipment on the other end and is establishing a connection. If it blinks for more than 5 minutes, see the troubleshooting instructions below.

DSL light flashing quickly green

The DSL light will turn solid RED if it can't detect the CenturyLink equipment on the other end of the line. If it stays red for more than 30 seconds, see the troubleshooting instructions below.

DSL light red

Troubleshooting the DSL light

If the DSL light on your modem remains offblinking, or red after a few minutes, there may be an issue with the network. Here are some things to try:

  1. Make sure your equipment is set up correctly and that your modem is not filtered. 
  2. Try rebooting your modem.
  3. If you have another phone jack in the house connected to your internet line, try connecting the modem to the other phone jack, in case the jack is faulty. 

 

If the problem continues, contact technical support for help.

Diagram of modem with green internet light

After the power and DSL lights turn solid green, the modem will establish a connection to the internet. The internet light will turn GREEN to let you know it's online. During normal use, the internet light will flash green whenever your modem is transferring information to and from the internet.


The internet light will be OFF (NO COLOR) if the modem hasn't been set up yet or programmed with credetials, or if it's in what is called "transparent bridging" mode. If it stays off for more than 30 seconds after the DSL light turns green, see the troubleshooting instructions below.

Internet light is off (gray)

The internet light will BLINK RED and GREEN when it is auto-detecting the internet configuration. If this continues for more than a minute, you may need to contact technical support to have your internet translated.

Internet light is blinking red and green

The internet light will be solid AMBER/ORANGE if the modem still needs to be activated. To do this, connect a computer directly to your modem, open up a web browser, and you should automatically be taken to the CenturyLink activation page. If you get "Page cannot be displayed," contact technical support.

Internet light is amber (orange)

The internet light will turn RED if it can't be authenticated, meaning the username and password are not accepted by the network. 

Internet light is solid red

If the light is red, do the following:

  1. Open a browser on a device that is connected to the modem, and go to http://192.168.0.1. This is the modem's user interface. 
  2. Select "Quick Set-up" and enter your your username and password to follow the steps for setup.
  3. If you don't know your username and password, try resetting your modem to factory defaults by pressing the reset button for 10 seconds, waiting for the internet light to turn on, then going through the CenturyLink activation process.
     

If the internet light is still red after resetting, contact technical support for help.

Diagram of modem with green Ethernet light

After the internet light is green, you are ready to get on the internet. The Ethernet light(s) will be solid GREEN if a device is connected by an Ethernet cable to the corresponding port on the back of the modem.


The Ethernet light(s) will be OFF if no device is connected to the corresponding Ethernet port.

Ethernet light is off (gray)

Troubleshooting the Ethernet light

If you do have a device connected to an Ethernet port, but the light is not coming on, try these tips:

  1. Make sure the Ethernet cord is fully plugged into both your computer port and the modem port.
  2. Try a different Ethernet port on the modem.
  3. Try another Ethernet cable if you have a spare.
  4. Make sure the Ethernet card on your computer is enabled. Search the help topics for your specific brand and model of computer to find out how to do this.

Diagram of modem with green WiFi light

As an alternative to using an Ethernet connection, you can use wireless to access the internet on your devices. The WiFi  light will be solid GREEN when WiFi is enabled and will flash or flicker whenever data is transmitted over the WiFi connection.


The wireless light will be OFF if the wireless transmitter in the modem hasn't been turned on.

WiFi light is off (gray)

To enable WiFi on your modem:

  1. Open a web browser on a device that is connected to the modem, and go to http://192.168.0.1.
  2. Select the Wireless Setup menu.
  3. Select Basic Settings in the left sidebar.
  4. Select Enable next to "Wireless Radio."
  5. Select Apply to save your changes.

The Wireless light will be solid AMBER/ORANGE if the wireless radio is in 'off' mode according to the wireless schedule feature. The wireless schedule allows you to set specific times for your wireless signal to turn on and off.

WiFi light is amber

If you want to adjust the wireless schedule on your modem:

  1. Open a web browser on a device that is connected to the modem, and go to http://192.168.0.1.
  2. Select the Wireless Setup menu.
  3. Select the Wireless Schedule option in the left sidebar.
  4. Make the desired changes by selecting the days/times to enable or disable the WiFi.
  5. Select Apply to save your changes.

Diagram of modem with green WPS light

WiFi Protected Setup (WPS) is an easy way to connect devices to your WiFi network with the press of a button. When the WPS light is GREEN, it is enabled and ready to connect. You can push the button to connect a WPS-compatible device to your modem's WiFi network without entering the SSID/passphrase on the device.


The WPS light will be OFF if WPS has been disabled.

WPS light is off (gray)

To enable WPS:

  1. Open a web browser on a device that is connected to the modem, and go to http://192.168.0.1.
  2. Select the Wireless Setup menu.
  3. Select the WPS option in the left sidebar.
  4. Enable WPS.
  5. Select Apply to save any changes.

The WPS button will BLINK AMBER/ORANGE while connecting to a device. If this continues for more than 2 minutes, try rebooting your modem.

WPS light blinking amber (orange)

The WPS button will BLINK RED if there is an error when connecting or if a session overlap is detected. If this continues for more than 30 seconds, try rebooting your modem

WPS light blinking red

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