Cox High Speed Internet & Apple IPv6 issue [3/2016]

Cox High Speed Internet & Apple IPv6 issue [3/2016]

Several of my clients and friends have reported a disruption of service with their ISP and home network, with two things in common:

  1. ISP:Cox
  2. Router/Gateway: Apple AirPort Express, AirPort Extreme, or Time Capsule.
SYMPTOMS: The modem is online, and appears to be functioning normally by the ISP/CMTS, and packets can be see being sent to and from the modem by the headend. However, upon boot/restart/release & renew, the Apple device acquires, but fails to maintain a valid DHCP lease from the ISP. AirPort Utility,  reports as having no connectivity what so ever. I suspect a process is crashing, as clients see the wireless network disappear and re-appear.

CONTROL: If you bring a different non-Apple router into the mix, while spoofing the same MAC address of the Apple device's WAN, so as to not have to power-cycle the modem; the non-Apple router will function normally. This can be confirmed by simply disconnecting the modem from the Apple AirPort/Time Capsule and directly plugging it into a computer, then power cycling the modem. After a few minutes the computer connected will receive a valid IP; verifying that the modem is operational. *If you change connected equipment to a cable modem, always power cycle it as the modem will bond with and learn the first MAC address it sees.

RESOLUTION: Disabling 
IPv6 Sharing on the Apple device will mitigate the issue until Apple or the ISP can produce a proper resolution.

This is an issue in which I have not seen since 5/2010. Back then, I hadn't been a cable jock for about 8 years. But as an ACN things were busy, when this issue surfaced, and I was the only person in town that had a fix. Long story short, last time it was isolated to a single router in a HUB that services a localized part of town. I've confirmed it's more widespread this time, hence this post. Both CCI and more importantly AI are aware and AI is working on a firmware with a TBD release date from what I'm told.

Enough! Get to the good stuff!


Make sure you have the latest available version of AirPort Utility, Apple Menu, App Store, Updates. Of course you do, because you check for, and install updates weekly, on top of automatically, right!?  As today 3/29/16, on a 10.10.5 machine, AirPort Utility 6.3.5(635.2) is the latest available.

  1. Connect the network in question via Wi-Fi or a wired network cable.
  2. From the Dock, click on Finder, then click the Go pull-down menu (top, left center), and select Utilities, then open AirPort Utility.
  3. Double click on your device connected to your cable modem. On version 6 AirPort Utility, it's represented graphically by being directly beneath the Internet icon.
  4. Go to Edit, Internet, Internet Options, then uncheck the "Enable IPv6 Connection Sharing" box, then click Save, then Update

The Apple device will restart and attempt to boot using the new settings. At this time, the router should come back online (with the familiar Green status light) in about 3-5 minutes. If your internet connectivity is not restored, see the Troubleshooting section below for details.


This process requires the App Store app AirPort Utility, click this link to jump there now. Note: You may need to first turn off Wi-Fi on your iPhone in order to download AirPort Utility for iOS. If you do not currently have access to an iPhone, data plan, or tethering option, then take your iOS device to network that you have authorized access to, then download AirPort Utility from the App Store. Then return to the location with AirPort/Time Capsule after downloading.To manually download, from your iOS device, open the App Store, tap Search, search for and download the free application "AirPort Utility" from Apple.

  1. Install AirPort Utility following the instructions in the above paragraph on your iOS device.
  2. From your iOS device that you installed AirPort Utility on, turn Wi-Fi on and connect the wireless network in question.
  3. Then open the AirPort Utility app on your iOS device.
  4. Tap on your Apple AirPort/Time Capsule directly below Internet, then Edit, Advanced, IPv6.
  5. On the option "Share IPv6 Connection" tap the slider so that it is Off/Disabled/on the left.
  6. Then tap Done, Done, Save/Update. 

The Apple device will restart and attempt to boot using the new settings. At this time, the router should come back online (with the familiar Green status light) in about 3-5 minutes. If your Internet connectivity is not restored, see the Troubleshooting section below.


  1. This requires that you have AirPort Utility downloaded and installed. Get it from here. Sorry folks, Windows 8 & 10 support is not there yet. Use a friend's iOS device if possible!
  2. Once AirPort Utility has been installed, connect to the network in question.
  3. Open AirPort Utility by clicking Start > All Programs > AirPort > AirPort Utility.
  4. Double click on the Apple AirPort/Time Capsule in question. Enter it's configuration password, if prompted.
  5. Click on Edit, Internet, Internet Options, then uncheck the "Enable IPv6 Connection Sharing" box, then click Save, then Update

The Apple device will restart and attempt to boot using the new settings. At this time, the router should come back online (with the familiar Green status light) in about 3-5 minutes. If your internet connectivity is not restored, see the Troubleshooting section below for details.


Hopefully by now, you know what the lights should look like when your cable modem is operating normally. If not, make a note of them now before proceeding, as odds are your modem is fine, if you're reading this.

If you have not already disabled IPv6, stop now and perform the steps from a section pertaining to what devices you have available in your situation above. If you have disabled IPv6, follow the steps as outlined below: 
  1. Locate the WAN port (Circle of Cirles icon) on your AirPort/Time Capsule. Disconnect the network cable from the WAN port (by depressing the retention mechanism, then pulling the network cable out).
  2. Locate the power adapter port (~ icon) on your AirPort/Time Capsule, and disconnect it as well.
  3. Power cycle your modem by unplugging the power cable for 10 or more seconds, then back in.
  4. For this next part, we need to wait for the modem to boot.
    Failure to do so could result in a further delay of internet activity as the AirPort/Time Capsule could get either an APIPA or private IP address from the modem before the modem establishes connectivity to the ISP

    So, after a brief period of 2-30 minutes, the lights on your modem should appear normal again.

    Example: If an Online, Globe, or World icon light is available, it should not be flashing, but on and solid.

    Once your modem is online, go ahead and move back to your Airport/Time Capsule, first plug-in the network cable from step 1, then the power adapter cable from step 2 back in, exactly in that order.
  5. After you plug your Apple AirPort / Time Capsule back into both power and the modem, it should only take 3-5 minutes for it to come back online, and your status light should be the familiar green once again.
  6. Only after the modem comes online, and your Apple AirPort/Time Capsule has booted, will the status light return to solid or flashing green  depending upon your configuration and *as long as all settings are valid/secure and systems functional.
Did this work? Let me know, I'm on Twitter...

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