BT Full Fibre IPv6 Provisioning

[sizzleplop]

I have recently switched to using a third party router - BT supplied the PPPoE details and I'm connected using IPv4 only. The original router (Smart Hub 3) was automatically setup for IPv6. I require IPv6 (for several BT business lines at different locations).

I have looked online and used the settings that have been seemingly been successful for many users. However, they do not work for this installation. It is my understanding that this service needs to be provisioned by BT for my line when using a third party router.

When I spoke with BT support on the telephone, I was told that I first needed a static IPv4 address - which I'm very sceptical about - but this has now been done.

I am using the following settings:

DHCPv6

Prefix delegation size: /56

Request prefix only: Disabled

Send prefix hint: Enabled

[sizzleplop]

I have tried various combinations, but only receive a fe80:: IPv6 address, rather than a 2a00: on the WAN interface. I'm happy to provide full details on the account, if that helps? Any assistance would be much appreciated. 

[sizzleplop]

Having read a couple of posts on here, it appears that @BethM may be able to assist - if not if someone else can that would be fantastic! 

[BethM]

Hi sizzlepop

I will need to query this with our technical team - can you please send over a private message with your account details? 

[sizzleplop]

Hi Beth,

thank you for your reply. I have messaged you with the details of the account. 

[sizzleplop]

We have a ball game! A big thank you to BethM for your assistance. Since BT don't provide any details, I would like to outline what's required for OPNsense configuration - to follow... 

[sizzleplop]

Step 0 — Initial OPNsense state

• WAN: PPPoE connected for IPv4 only

• IPv6 previously disabled globally on OPNsense interfaces

• Neighbor Discovery (NDP) was disabled

• WAN interface showed only fe80::…

• DHCPv6 logs were empty

• LAN IPv6 not yet configured

Symptoms:

• No global IPv6 address on WAN

• No IA_PD prefix delegated

• DHCPv6 client never started

[sizzleplop]

Step 1 — Enable IPv6 globally

• Interfaces → Settings → Allow IPv6 → Enabled

• DHCP Unique Identifier → use existing LLT DUID

• Log level → Standard Info

✅ This allows OPNsense IPv6 stack to start on all interfaces.

[sizzleplop]

Step 2 — Enable Neighbor Discovery

• Interfaces → Neighbors → Automatic Discovery → Enabled

• Reason: required for IPv6 RA / NDP / SLAAC to work correctly on LAN

[sizzleplop]

Step 3 — Configure WAN IPv6 client

• Interfaces → WAN → IPv6 Configuration Type → DHCPv6

• Request prefix only → ✅

• Send prefix hint → ✅

• Prefix delegation size → /56

• PPPoE username/password → correct