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Message 1 of 9

IPv6 dynamic /56 prefix

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So does anyone know a good modem/router combo that supports the very non standard BT 'Special' IPv6 dynamic /56 prefix ?




  • Because monopoly is just a game.
  • They luv me posting here.
  • My  broad band is a bit slow.


Feel free to rearrange these three sentences in order of conspiracy.



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Message 2 of 9

Re: IPv6 dynamic /56 prefix

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I gave you 21 minutes of my life and now I want a refund.

I asked Cortanna but she had a headache, so I asked Alexa only  she was out doing her nails so finally I had to ask Google and she said this was far too nerdy and would I like to look at a picture of a cat.

So here we are:1up.jpg

And this is the future

..............and it has got knobs on.

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Message 3 of 9

Re: IPv6 dynamic /56 prefix

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My Asus DSL-AC68U works just fine with BT's implementation of IPv6 as would the Asus DSL-AC88U. My AC68U looks far less futuristic than the TP-Link in your post.

Message 4 of 9

Re: IPv6 dynamic /56 prefix

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Hello Mr Curtiss and thank you.😁

Do they all do do 'ppoev6' ? I've been told that's a must to get the 'special' bt ipv6.

£300+ squids for native ipv6 is a lot to HAVE to spend.

Seems to me bt like it hot.


Normally I would say Boom Boom but your probably not old enough.


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Message 5 of 9

Re: IPv6 dynamic /56 prefix

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My kids would get the Boom Boom reference so I guess that makes me old enough 🙂

All I can say about the ppoev6 is that my AC68U quite happily gets an IPv6 /56 IP Address and at £130 is a sound investment.

If you were to go the UltraFast route which uses G.Fast then the AC88U at around £190 would be the option.

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Message 6 of 9

Re: IPv6 dynamic /56 prefix

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Mr Curtis - You've Cracked It - 😀

Tp Link are the Bees Knees for bt natives. I didn't know that. 

Now I must mark your answer as the right one.

And 'cause you must be very old here's a picture to say thank you & cheer you up. It's a reminder of the old days:


Hot Stuff_.jpg


We were all so happy. One big happy family. Bt wasn't around. Letters arrived the same day.

Plastic was good and children hadn't yet been invented.

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Message 7 of 9

Re: IPv6 dynamic /56 prefix

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Nope looking around some more I just decided I want this modem:



It's called Doreen does 75wpm makes coffee and doesn't ever get baud.

Message 8 of 9

Re: IPv6 dynamic /56 prefix

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My kids don't post here.

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Message 9 of 9

Re: IPv6 dynamic /56 prefix

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Hi folks... I happened across this page whilst looking for info on how to hook up my home made firewall with BT's IPv6 service over UltraFast broadband.

There seems to be scant information about how to do it so I thought I'd contribute some info on how I configured my OpnSense firewall software on a small 8 port Kettop router.

Step1: Configure your WAN interface for PPPoE as normal

  • Username:
  • Password: bt

Step2: Enable DHCPv6 on the WAN interface

  • Enable prefix delegation (DHCPv6-PD) with a size of /56 to get a range of addresses allocated to us
  • Configure to "request only a prefix"
    • BT don't allocate individual global IP's to the WAN interface so don't try get one from DHCPv6.
    • We will use the link-local address that the router allocates itself.
  • Gotcha in OpnSense:
    • You also need to tick "use IPv4 connectivity" otherwise it tries to DHCPv6 on the underlying ethernet instead of the PPP link.

Step3: Enable IPv6 on the LAN

  • There are a couple of options here... DHCPv6 or SLAAC
  • If using SLAAC, the router should automatically assign a /64 from the /56 assigned to us by BT.
    • The router will periodically announce itself on the LAN with the link-local /64 prefix
    • Hosts are responsible for allocating their own global addresses using this /64 prefix
  • If using DHCPv6, you may need to allocate a chunk of the /56 prefix manually for the DHCPv6 server. Some router software will do this automatically in the same way as for SLAAC.
  • The OpnSense IPv6 LAN config type that worked for me was "track interface" using the WAN interface