How to restart your modem

With any modem or SmartNID, a quick restart can often fix many connection and wireless issues. So this is one of the first things to try if you're having trouble with your Quantum Fiber internet. You can restart manually or through the app.

bottom view of C5500XK smartNID

NOTE: If you have a wall-mounted C5500XK or C6500XK SmartNID, please be careful when restarting. Do not unplug the green wires on the bottom of the device. These are part of the fiber connection and should not be disconnected.

How to restart from the app

You can restart your modem remotely through the Quantum Fiber app. 

  1. Sign in to the app and go to the Support section and find the Troubleshooting area and tap the Restart Modem button.

  2. You'll be asked to confirm that you want to restart. If you do, go ahead and tap Restart.
App restart screen 1
App restart screen 2
  1. Wait while the modem restarts. This can take up to 5 minutes. You can close the app if you want and the restart will complete.

  2. Once the modem has booted up, you'll see a success message. Select Close to return to the main support screen.
App restart, screen 3
App restart, screen 4

How to restart manually

To restart your modem manually, follow these steps:

  1. Unplug the power cord from the back of the modem or the bottom of the SmartNID. Make sure you have unplugged the correct cord by checking that all the lights on the equipment go OFF.
  2. Wait for at least 30 seconds, then plug the power cord back in. 
  3. Wait 2-3 minutes for the modem to fully boot up. The power light and the internet light should turn green if you have a tower modem. In the case of a C4000XG or SmartNID, the single light on the front will turn green when it's connected.  
  4. Check again for a connection. You should now be able to get online.
C4000 with green status light
C3510XZ modem

You'll know you can get back online once the light(s) on the front of the modem turn green.


The WiFi connection on your smartphone (and other devices) will be interrupted when the modem shuts down. Once the network is back up, your WiFi network will come back online and your devices will connect automatically if they are set to remember the network settings. Or you may need to reconnect some of your devices manually.

What to do if a restart doesn't help

You may want to try a full modem reset, which returns the modem to its factory default settings. If you have a C5500XK or C6500XK SmartNID, contact us for tech support before attempting a reset.

Need more help? The best way to contact us is through the app or the account portal. You can also email or call us if you prefer. 

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