Unable to get IP v6 working

[sujop]

I am from New Zealand. My broadband provider is 2degrees. I am trying to get IPv6 working on Opnsense 24.1.6 with no luck. IPv6 previously worked on opnsense 23.xx but stopped working after an update somewhere around March 2023. Since then I have tried multiple times with different Opnsense versions with no success. Clients on LAN receive IPv6, but cannot access any IPv6 websites on internet. Pinging IPv6 hosts on internet fails with  timeout. I can ping any IPv6 address within LAN but not on the Internet.

IPv6 works fine with pfsense, with the same internet provider, but not with opnsense. given below is the relevant selected options to enable IPv6 in opnsense.

[WAN]
IPv4 configuration type: DHCP
IPv6 Configuration Type: DHCPv6
Prefix Delegation size: 56
Use IPv4 connectivity: Yes

[LAN]
IPv4 Configuration type: Static IPv4
IPv6 Configuration Type: Track Interface

Track IPv6 Interface
IPv6 Interface: WAN
IPv6 Prefix ID: 0
Allow manual adjustment of DHCPv6 and Router Advertisements: Yes

Services:Router Advertisements[LAN]
Router Advertisements: Unmanaged (I have tried other options as well)
Advertise Default Gateway: Yes
Use the DNS configuration of the DHCPv6 server: Yes

I have tried almost everything that has been suggested on the internet for similar issue, with no luck. Please note that IPv6 works flawlessly on pfsense.

Also my ISP requires vlan tagging. Hence, my WAN interface is assigned to vlan01(parent: igc0, tag: 10)
vlan is configured with parent igc0 and VLAN tag: 10

A fix for this issue was implemented as per https://github.com/opnsense/core/issues/7202, I think. However, at least for me the issue persists.

Apologies if I am confusing you.

Any help will be appreciated.

[sja1440]

I'm not an expert on ipv6 but two days ago I began using ipv6 with my provider for the first time and so the experience is very recent.

A couple of questions:

(1) On the Interfaces section of the Dashboard, you should see some ip addresses for your WAN interface: an ipv4 together with a ipv6 one.  Is the ipv6 address present?

(2) From an internal pc, what are the first eight hex characters of the ipv6 addresses that are assigned to your PC? Don't send the full addresses since that might identify you - just the first 8 hex characters

After doing the above please try setting:
* Router Advertisements[LAN] to stateless.
* Router Advertisements[LAN]  Use the DNS configuration of the DHCPv6 server: no
* DHCPv6 [LAN] disabled

Disconnect your PC from the LAN and then reconnect. What do you see now for your PC's ipv6 addresses?

[sujop]

I was trying to follow your instructions and I accidentally unticked Request an IPv6 prefix only, and IPv6 started working. To verify that was the issue, I ticked Request an IPv6 prefix only, unplugged the WAN cable and IPv6 would not work. Strange.