Open Radar

 
Summary:
I have an AirPort Time Capsule that I'm using at home as my Internet router, connected to my Comcast Xfinity modem. IPv6 works fine with it, usually. But after some random number of days or weeks, I notice that I'm no longer able to establish new IPv6 connections to the public Internet from my Mac Pro or my MacBook (both of which are connected to the router, one by ethernet cable, one by WiFi). When I notice I've lost IPv6 capability, websites like http://test-ipv6.com/ no longer say that I'm IPv6 capable.

I also lose the ability to `ping6` any public Internet IPv6 address (like Google Public DNS: 2001:4860:4860::8888), though I can still `ping6` the IPv6 WAN address both from my LAN hosts and from remote hosts on the public Internet. So, I'm convinced that this is not a Comcast problem, because the WAN address is still responding to ping6.

Using Wireshark, I obtained a packet trace of the problem, but it was uninteresting: all it shows is my IPv6 TCP connection requests being made, without any responses coming back.

Using AirPort Utility, I carefully examined all the relevant panes of configuration information, but nothing is amiss or has changed when the problem is happening. The only way I've discovered to fix the problem is to power cycle the AirPort. After power cycling, IPv6 function is always successfully restored, and the only configuration information that has changed in AirPort Utility is that new IPv6 addresses have been obtained.

Steps to Reproduce:
I don't know how to cause this problem to occur. It seems to occur randomly, days or weeks after power cycling the AirPort. It has happened about 6 times, total, in the couple years that I've owned the router.

Expected Results:
I expect the AirPort to never lose IPv6 functionality.

Actual Results:
Sometimes, the AirPort loses IPv6 functionality, forcing me to power cycle it to restore the functionality.

Version:
AirPort Time Capsule model A1470
firmware version 7.7.7

Notes:
[none]

Configuration:
[none]

Attachments:
[none]