opnsense noob, I want to configure IPv6

[mrt12]

Good day,
so I have the following setup. I have glass fibre FTTH. The ISP modem is very crappy, so I wanted to replace it by opnsense. I run the opnsense on my Proxmox server. The ISP modem is set to bridge mode, i.e. it is only sort of a "media converter" from glass fibre to RJ45. This is then connected to opnsense.

So far, it worked more or less out of the box: the WAN interface gets its WAN address, both IPv4 and IPv6.
I also enabled the DHCPv4 server, which also works very well. My LAN clients get their IPv4 configured, and also the DNS server and default gateway. Very good!

But now comes the trouble. On my LAN client, I can use IPv4, but IPv6 does not work at all. I have the following config:

a) under Interfaces -> Overview, I can see:


interface: WAN (wan)
link type: dhcp
ipv4: 80.xx.xx.112/21
ipv6: fe80::be24:11ff:xxxx:xxxx/64
gateway: 80.208.xxx.xxx, fe80::200:5ff:fe02:1

to me, the noob I am with IPv6, this looks good, as obviously opnsense gets its address configured automatically by the ISP. Perfect!

Then, I have configured:
Interfaces -> LAN -> IPv6 connection type -> track interface
Interfaces -> LAN -> track IPv6 interface -> WAN, prefix ID 0, allow manual adjustment
Interfaces -> WAN -> IPv6 config type -> DHCPv6
Interfaces -> WAN -> DHCPv6 client config -> request only prefix, prefix delegation size 57, send IPv6 prefix hint, use IPv4 connectivity.

I have NOT activated the Kea DHCPv6 Server, but I have enabled the router advertisements. I have configured
Router advertisements -> LAN -> managed advertisements, advertise default gateway, use DNS config from the DHCPv6 server.

What irritates me now a lot is the following:

I can, on a client in the LAN, do the following

ping -4 google.com

and he can resolve the IPv4 and ping works fine.
However, if I try the same with IPv6, so

ping -6 google.com

he still can successfully resolve the IPv6 address, and then ping just waits forever. No response, no nothing. How is this possible?
Also I visit in the browser the webpage https://test-ipv6.com/ and he can detect my external IPv4, but reports "you have no IPv6 connectivity". Which is weird.

When I disable the bridge mode of the ISP's modem and use it as normal router, it sends router advertisements and configures my LAN hosts with IPv6 and then the full IPv6 connectivity works. But not with opnsense. I wonder where I did the misconfiguration or if just my router is so shitty that it does not work properly?

Can anybody please help?

thanks a lot!

[klingon888]

I struggled a bit too but followed the steps on this post https://forum.opnsense.org/index.php?topic=32741.0 and it worked for me. But I use SLAAC instead of DHCPv6 for the LAN. If you want SLAAC, for Router Advertisements, just set to "Unmanaged" and leave the rest as default.

I'm no expert but I noticed your prefix delegation size is 57. Is that correct? I typically only see 56 or 64.

[mrt12]

>> I'm no expert but I noticed your prefix delegation size is 57. Is that correct? I typically only see 56 or 64.

I am no expert either. But from tech support from my ISP i know tgey give a /56 prefix.
Somewhere I saw the info that I shall use one bit more for the delegation. Is that wrong?

the reason why I used DHCPv6 was that I have a pihole DNS server which blocks common ad and malware servers, so I want all my internal hosts to use this as DNS and not the opnsense. For DHCPv6 I could specify the DNS server.