No IPv6 trafic

Installing and Using OpenWrt
1

I have an OpenWrt box that get the internet signal from a modem put in
bridge mode. Trafic on IPv4 works, but IPv6 doesn't. However, I get a
public IPv6 address on the box. If I ping a host from the OpenWrt box itself, I
get no response:

$ ping vg.no

PING vg.no (2001:67c:21e0::16): 56 data bytes

I tried to connect a Linux PC directly to the modem, and at first, I
got the same result. But after doing dhclient eno1 the trafic on
IPv6 worked.

Now, I wonder how I can get the wan6 interface on the OpenWrt box set
to work.

I've tried to set the option reqprefix in /etc/config/network to
different values, like 64, 62, 60 and 56, I rebooted the box, but with no changed result.

The output of ip a

...

12: eth0.2@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UP qlen 1000
link/ether e8:de:27:ff:af:7a brd ff:ff:ff:ff:ff:ff
inet 84.213.197.142/20 brd 84.213.207.255 scope global eth0.2
valid_lft forever preferred_lft forever
inet6 2a02:fe0:c100:6:eade:27ff:feff:af7a/64 scope
global dynamic noprefixroute
valid_lft 2591996sec preferred_lft 604796sec
inet6 fe80::eade:27ff:feff:af7a/64 scope
link
valid_lft forever preferred_lft forever

Do you have any suggestions on how to fix the problem?

2

It seems likely that the bridge (or pseudo-bridge?) only supports SLAAC. DHCPv6 usually configures /128 addresses but I can't see any in "ip a". And routers usually acquire dynamic addresses with DHCPv6-PD, which may not be supported. (You should get more information about the wan6 status with "ifstatus wan6",)

(I guess you could use the relay mode as a work-around if your ISP doesn't support DHCPv6-PD.)

3

Thanks for your suggestion. After fiddling a bit more, I found that it's the firewall that is blocking the traffic. I'm using a nft script, and I have to look more into it to find the cause.