How to configure router for ipv6 with bridged modem?

[jamames]

Hello,

I have a docsis 3.1 modem (CV8560E) and a WRT32X running a fresh install of 24.10.5.

I have the modem set to bridged mode and IPv4 works, but IPv6 does not. I’ve confirmed with my ISP that IPv6 is supposed to work. https://test-ipv6.com/ shows a 0/10 score.

I can currently see on the modem’s settings page that it gets an IPv6 address:

In OpenWrt’s Interfaces page, I see this:

I’m not sure if the problem is because PD is /57 and not /56?

I tried adding the entire prefix from the modem’s settings to the router’s WAN6 request prefix config but it didn’t seem to change anything.

/etc/config/network (should have mostly default settings)

config interface 'loopback'
option device 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'

config globals 'globals'
option ula_prefix 'fd3f:135d:a8fb::/48'
option packet_steering '1'

config device
option name 'br-lan'
option type 'bridge'
list ports 'lan1'
list ports 'lan2'
list ports 'lan3'
list ports 'lan4'

config interface 'lan'
option device 'br-lan'
option proto 'static'
option ipaddr '192.168.1.1'
option netmask '255.255.255.0'
option ip6assign '60'

config device
option name 'wan'
option macaddr 'redacted'

config interface 'wan'
option device 'wan'
option proto 'dhcp'

config interface 'wan6'
option device 'wan'
option proto 'dhcpv6'
option reqaddress 'try'
option reqprefix 'auto'
option norelease '1'

/etc/config/dhcp (should have default settings)

config dnsmasq
option domainneeded '1'
option localise_queries '1'
option rebind_protection '1'
option rebind_localhost '1'
option local '/lan/'
option domain 'lan'
option expandhosts '1'
option cachesize '1000'
option authoritative '1'
option readethers '1'
option leasefile '/tmp/dhcp.leases'
option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
option localservice '1'
option ednspacket_max '1232'

config dhcp 'lan'
option interface 'lan'
option start '100'
option limit '150'
option leasetime '12h'
option dhcpv4 'server'
option dhcpv6 'server'
option ra 'server'
list ra_flags 'managed-config'
list ra_flags 'other-config'

config dhcp 'wan'
option interface 'wan'
option ignore '1'

config odhcpd 'odhcpd'
option maindhcp '0'
option leasefile '/tmp/hosts/odhcpd'
option leasetrigger '/usr/sbin/odhcpd-update'
option loglevel '4'
option piofolder '/tmp/odhcpd-piofolder

What setting am I missing in order to get this to work?

I found this related post No ipv6 on LAN hosts - #13 by woutercoppens who has the same modem and provider I have. But my settings are the same as his.

[brada4]

Set delegation hint to /64
You painted over so much that noone can tell wif openwrt pd overlaps with CPE LAN pd

[jamames]

Sorry, I’m not sure how much needs to be private or not.

Under Interfaces → Lan → Advanced Settings → IPv6 assignment hint, I changed it to 64, but still receive 0/10 on https://test-ipv6.com/

[woutercoppens]

We're currently on holidays and I'll post my config when we're back. I'll also do the ipv6 tests

[egc]

Is your client setup to use IPv6?
If you are using a windows client you can view this with:
ipconfig /all

[jamames]

Yes, client is my main pc running windows 11. IPv6 is confirmed enabled.

I’m not able to ping IPv6 addresses (I used 2001:4860:4860::8888 which I think is Google’s DNS) from either my pc or from the router directly. They both timeout

[egc]

The modem itself also seems to have an own IPv6 and IPv4 address is it really in bridge mode?

Have you tried to power down modem and router, wait 3 minutes power up modem, wait 3 minutes and power up router?

I have an other docsis 3.1 modem so cannot compare, but the routers settings are identical to mine and I have IPv6 and IPv4 working

[jamames]

Yes, it’s in bridge mode

And yes, I have powered down both the modem and router and waited a few minutes.

I feel like I’m close to the solution and that it’s probably a single setting somewhere I’ve missed

[mk24]

What you have shown so far looks good. Try a ping6 openwrt.org from the router.

The WAN has a /57 prefix, which is enough to delegate a /60 or /64 to the LAN. Check the lan interface has an IPv6. It is not a /56 likely because the wan itself has been given an IP from the same /56, which means that the whole /56 is no longer available and it has to be split down into a /57.

Showing bits 48 to 64 in the IPs helps to debug the delegation. In other words don't redact the fourth group of hex marked P: AAAA:AAAA:AAAA:PPPP:LLLL:LLLL:LLLL:LLLL Redacting the second two groups of As will keep your privacy.

[jamames]

are the LLLL groups safe to keep or should I redact them too?