ipv6 on archer c7

[john9411]

Still cannot get this to work with Vigor 130 + Archer C7 combo.

Have connected BT Smart Hub and both IPv4 and IPv6 work as expected.

Have tried all manner of combinations of settings on C7 and even tried Vigor in 'Bridge' mode rather than PPoE (even though Draytek say it should not make any difference!) but still no joy. I did, on just one occasion, get a 'tick' in 'Status' on C7 for both IPv4 and IPv6 but when going to IPv6 test sites it said IPv6 no enabled!

Am still liaising with TP-link over problem as they say it should work.

Come to conclusion that either have faulty C7 (how do I prove this as everything else; DNS, Port Forwarding etc. etc. all work as expected) or TP-link are being economic with the truth!

Really ironic thing is that I bought Vigor and C7 from BT Shop!!!!

[john9411]

After exchanging numerous emails with TP-Link support and following my suggestion to them that the prefix delegation may be the cause of the problem I have now received the following reply,

Thank you for your update. I just come back from our holidays.
Actually BT will assign a 56 bit prefix delegation to customer's side.Then routers should transform it to 64 bit because most clients can only recognize 64bit prefix. So this is not the reason.

I often handle IPV6 case arround the world. 2 years ago, I know BT will assign a 64 bit prefix(for wan) and 56 bit prefix delegation(for lan) to his customer. But now, it seems BT has changed its IPV6 network. BT only assign a 56 bit prefix delegation. I guess that's is the reason but I will ask a remote assistant to double check. Most routers cannot handle the case without wan IPV6 address.

BT hub can follow the changes of IPV6 network because it's provided by ISP itself but we need some time to support it.

I take this to mean that TP-Link are suggesting that BT has modified its IPv6 network to change prefix delegation and is now not currently supported by Archer C7 and other routers.

Anyone care to comment?

[john9411]

Thank you for your update. I just come back from our holidays.
Actually BT will assign a 56 bit prefix delegation to customer's side.Then routers should transform it to 64 bit because most clients can only recognize 64bit prefix. So this is not the reason.

I often handle IPV6 case arround the world. 2 years ago, I know BT will assign a 64 bit prefix(for wan) and 56 bit prefix delegation(for lan) to his customer. But now, it seems BT has changed its IPV6 network. BT only assign a 56 bit prefix delegation. I guess that's is the reason but I will ask a remote assistant to double check. Most routers cannot handle the case without wan IPV6 address.

BT hub can follow the changes of IPV6 network because it's provided by ISP itself but we need some time to support it.

[john9411]

I take this to mean that TP-Link are suggesting that BT has modified its IPv6 network to change prefix delegation and is now not currently supported by Archer C7 and other routers.

[john9411]

Anyone care to comment?

[PinkSquirrel]

It makes sense that BT may have made changes because as I said in a previous post in this thread ipv6 was working with my router and then it stopped. On the other hand I'm surprised more people haven't reported problems in this forum.

I also have a case open with tp-link support so it will be interesting to see if they come to the same conclusion.

[john9411]

If this does need firmware upgrade from TP-Link it could be some time before we get a resolution.

In the interim can anyone recommend a router that is currently working OK for both IPv4 and IPv6 on BT as for technical reasons I need a quick fix. Also got Archer C7 from BT themselves so may try and negotiate a swap!

[john9411]

Still no resolution to this problem so contacted TP-link to say that, as far as I am concerned, I now consider the router faulty as it does not do what it is supposed to do.  I also asked for a 'fault' reference so I could return router to BT Shop as I am outside the exchange period. Their response was that router is IPv6 certified and that if BT's network is not standard then that is not TP-link's problem. They suggest that I ask BT Shop nicely if they will still exchange but, if not, to let TP-link know and they will contact their UK rep to see what he/she can do. This begs obvious questions:

- BT network not standard?

 -If BT Shop agree to exchange what do I get instead that is guaranteed to work?

- If used, what can their UK rep do?

I shall report back in due course.

[licquorice]

BT implement IPv6 as /56PD whereas many ISPs implement /64PD. Both are legitimate implementations.

As far as I'm aware the ASUS DSL AC68U and DSL AC88U support /56PD, I'm sure @TimCurtis will be along to confirm.

I'm also fairly sure other TP Link models also support /56PD and TP Link support are being somewhat disingenuous with their comments.

[john9411]

BT Shop has agreed to take back Archer C7 and refund - tick!

As already have Vigor 130 modem am only looking for router and am looking at ASUS.

As ASUS DSL AC68U and DSL AC88U support 56/PD I wonder if it is safe to assume that ASUS  RT-AC86U also does?

@licquorice  - judging by my experience with TP-Link I couldn't agree more with your comments and am now reluctant to buy another TP-Link product.  I have to say, though, that judging by my and others experiences with BT over 'latency' (XBOX and Netflix forum refers) I am also not that enamoured with BT - and that from a BT pensioner who worked for them for almost 30 years!

[licquorice]

Yes, as far as I'm aware, the RT versions are just the same as the DSL versions but without the modem.

Only 30 yrs, I had 41 yrs penal servitude!! 😀

[john9411]

Have just received following from TP-Link.

++++

Thank you for your valuable reply. As I say before, this issue is not related with prefix delegation because we can handle different prefix delegation.
We just do a capture on one customer's network who is also using BT network today. This is exactly the same as what I known before. The M flag in RA is 1 which means the IPV6 gateway states he will offer IPV6 address through DHCPV6 protocol. But when we send DHCPV6 request to it, the gateway replys "NoAddrAvail". This is not reasonable if it tells us M flag is 1.
I have seen this case in other region but it's very rare. I guess some ISP will only assign the IPV6 address to his own device but not third-party router. Our router will support this kind of network in the future.

If you want to use our router and IPV6 function, I'm afraid that you need connect a BT Hub in front of C7. C7 should enable IPV6 passthrough function to provide IPV6 for your clients. I think this is a temporary solution for now.

+++++

2nd paragraph too technical for me plus have now returned router to BT Shop.

3rd paragraph concerns me as they are implying that BT's iPv6 will only work with BT's own equipment!!!

Also have no great desire to use BT Hub  so still investigating other options - ASUS looks best bet at the moment but still concerned by what TP-Link say in that 2nd and 3rd paragraph. If anyone can enlighten me it would be appreciated.

[john9411]

Have also now received following from ASUS

++

Thank you for contacting Asus support

No specific /56 support unfortunately

As it is usually hardcodes to expect /64 prefix, so it might cause issues 

++

Others have said Netgear will not work either.

I have also noted that the bulk of posts where IPv6 is working are now quite old.

It would be useful to know if anyone currently has IPv6 working OK on non BT equipment or has BT been sneaky and change something so it will only work with their own products?