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.