Why does my Airport Extreme hate IPv6?

I’m fortunate enough to have an ISP that provides IPv6, and a cable modem that supports it. While there’s a router built into the modem, I have an Apple Airport Extreme that I’d rather use because it–and many of my devices–support 802.11ac, while the cable modem’s wifi does not. Despite that, I’m forced to use the cable modem’s routing, and put the Airport into bridge mode, otherwise nothing connected to the Airport receives an IPv6 address.

The issue is utterly perplexing, because in bridge mode, the Airport does distribute both IPv4 and IPv6 addresses. If the Airport is handling routing–failing to distribute IPv6 addresses–I can connect another device directly to the cable modem and receive an IPv6 address without fail. So, the network exists in this annoying split state, where the cable modem handles routing and the router only handles wifi.

If anyone’s wondering why I care so much about IPv6, the answer is simple: most of my neighbors seem not to be using that side of the network. In the evenings and on weekends, the IPv4 half of our connection can slow considerably compared to its IPv6 counterpart. Fortunately, Netflix is fully available over both (goodbye buffering) as are an ever-increasing number of sites and services.

6 thoughts on “Why does my Airport Extreme hate IPv6?”

  1. I’ve been using Airport Extreme’s and Time Capsule’s with IPv6 for several years now, and while I’ve never pointed to it as the cause of any connectivity issues I’ve ever had over the years, between both Time Warner and Verizon FiOS I haven’t need to do anything particular special to get it to function.

    At home I’m currently extending one Time Capsule to 3 other Airport’s at each corner of the house, with no issues. At the office, I have a Time Capsule in bridge mode plugged into the greater wired network of the building. In Providence I had Gigabit speeds jacked into my old apartment, and my Time Capsule enjoyed every IPv6 minute of it. When WordPress.com rolled out IPv6 support, I believe I was one of the first ones visibly in the logs with genuine IPv6 traffic end-to-end, all with these same Airports.

    My hunch would be the firmware is wonky, the hardware is foul, your ISP is provisioning something weird, or maybe DNS or proxy is getting in the way. I mean, there really isn’t much else to check, but trying different (and new) hardware is a cheap way to eliminate one big gray area.

    1. A hardware issue is my fear. I’ve reset the Airport more times than I can count, and the same devices work when connected directly to the modem/router. Perhaps I’m due to research new routers.

  2. I had your same setup for a while (AT&T U-Verse, which is not so great), but my issue there was that the cable modem’s router does not support any port forwarding protocols like NAT-PMP or UPnP which was annoying because I’d have to manually forward ports for programs at that point.

    What I did is change the cable modem router to be in DMZ mode pointing all traffic to the Airport’s IP address. The problem is that I lose IPv6 at this point (as DMZ is implemented over IPv4 internally I guess?).

    That’s my setup at this point. Not having IPv6 isn’t a killer for me at this point since the internet is DSL anyways. But it would be nice to have a “best of both worlds” configuration; not sure it’ll happen with this AT&T router though 🙁

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