Using IPv6 with TP-Link routers and Zen Internet

So, after quite a lot of time of trial and error, I’ve finally managed to get my TP-Link Deco routers working with an IPv6 connection to my ISP, Zen Internet.

Zen’s instructions on it are vague, and really only tell you anything relevant for their own-provided router (although, even those instructions appear to have now gone from their site).

I’m going to share what I did here, as it may help others, even if your configuration is not the same as mine (so, settings it up for Zen on another router, or setting up another ISP on a Deco router).

Why switch to IPv6?

I could repeat it here, but this is a good write-up on the benefits of using it.

IPv6 offers exciting possibilities for smoother connections, faster communication, and a more secure online experience.

The Journey So Far

First of all, you need to let Zen know that you want to use IPv6. They’ll switch it on and, when I did it in 2015 (yes, I’ve been struggling with it since then!), send you an email with details.

Thank you for your email. Your subscriber account has now been enabled for IPv6. The new attributes will take effect next time the session is restarted. Your IPv6 address details are;

ND Prefix: [redacted]::/64
PD Prefix: [redacted]::/48

The two prefixes are described below, along with some further information on the Zen IPv6 service:

/64 Neighbour Discovery (ND) Prefix. This is used to automatically address the WAN interface of your Router, or if you are directly connected without a router, the WAN interface of that device.

/48 Delegation Prefix. This is usually provided over DHCPv6, and requires that your router acts as a requesting router for the purpose of IPv6 delegation RFC3633 – (https://tools.ietf.org/html/rfc3633). Subnets of this prefix are used by the CPE to address devices on the LAN. If prefix delegation is not supported on the router, a suggested interface ID and static route is available, which should allow routing to take place.

We also have an IPv6 enabled DNS Resolver ([redacted]) , the IPv6 Address of this will be automatically advertised to supporting routers RFC3646 (https://tools.ietf.org/html/rfc3646). It can also be configured manually if required.

Routers supporting RFC7084 (https://tools.ietf.org/html/rfc7084) are expected to work without issue. Older routers, or ones that do not fully implement RFC7084 may experience issues.

Okay. Nice. Very technical and not really helpful as none of that matches up with router settings. I put this to one side for 4 years.

I messaged Zen again in 2019 and they provided the above details again, but with additional links to setting up on their routers (and none of those links now work). Otherwise, Zen won’t help as I’m using a “third party” router. To be clear, telling me how the setup aligns with the settings with my router’s, which I can provide to them, I do not think is something beyond their capability. Never-the-less, despite more and more people using their own routers they are stubbornly refusing to assist.

Now I’m back and determined to crack it!

The Breakthrough

What really helped was this forum post where somebody shared how they’d set up their ISP (not Zen) with IPv6 on the Deco. They listed the settings they used, which I tried and… it didn’t work. But it made sense. The problem is that depending on which early option to choose (e.g. the connection type), the other settings that are available then change.

Anyway, that was the issue here. My IPv4 account was using PPPoE, so matching that here helped. The only thing I had to change different to the forum to then get it to work was how the IPv6 address was fetched – I changed this from “Stateful” to “Auto” and that was it.

The Settings that Gave me IPv6

Here’s the full, working settings for Deco and Zen…

To test head to a website such as https://test-ipv6.com/, which will confirm whether the settings are working.