[Fixed] IPv6 Router Advertisement doesn't appear to work

[Yggdrasil]

Hi, my RT-AC66U with firmware 380.57 has a working IPv6 connection with my ISP via 6rd. Router Advertisement doesn't appear to work, despite the logs saying it's enabled.

I've run Wireshark on a few LAN hosts and don't see any RA packets on the network. Hosts are not autoconfiguring themselves. Weird, since the messages in syslog (see below) seem to indicate they should be broadcasting. This leads me to believe the packets are not actually getting sent.

The router can ping6 outside addresses just fine. Also, hosts on the LAN that have a static v6 address can reach both internal and external v6 hosts just fine. Static hosts have no trouble performing Neighbour Discovery.

I've rebooted several times and disabled and enabled RA to no effect.

Here's a snippet from the syslog, on a reboot:

Aug  1 00:00:17 dnsmasq[268]: started, version 2.76-g41a8d9e cachesize 1500
Aug  1 00:00:17 dnsmasq[268]: warning: interface tun21 does not currently exist
Aug  1 00:00:17 dnsmasq[268]: warning: interface ppp1* does not currently exist
Aug  1 00:00:17 dnsmasq[268]: asynchronous logging enabled, queue limit is 5 messages
Aug  1 00:00:17 dnsmasq-dhcp[268]: router advertisement on br0
Aug  1 00:00:17 dnsmasq-dhcp[268]: IPv6 router advertisement enabled
Aug  1 00:00:17 dnsmasq[268]: read /etc/hosts - 6 addresses
Aug  1 00:00:17 httpd: start httpd
Aug  1 00:00:17 httpd: start httpd - SSL
Aug  1 00:00:17 crond[272]: crond: crond (busybox 1.20.2) started, log level 8
Aug  1 00:00:18 syslog: Generating SSL certificate...
Aug  1 00:00:19 disk monitor: be idle
Aug  1 00:00:19 hour monitor: daemon is starting
Aug  1 00:00:19 hour monitor: ntp is not syn
Aug  1 00:00:21 Samba Server: daemon is started
Aug  1 00:00:23 kernel: Ebtables v2.0 registered
Aug  1 00:00:24 kernel: IPv6 over IPv4 tunneling driver
Aug  1 00:00:24 dnsmasq-dhcp[268]: router advertisement on 2a01:670:6a53:5f00::, constructed for br0
Aug  1 00:00:26 start_nat_rules: apply the nat_rules(/tmp/nat_rules_eth0_eth0)!
Aug  1 00:00:27 kernel: nf_conntrack_rtsp v0.6.21 loading
Aug  1 00:00:27 kernel: nf_nat_rtsp v0.6.21 loading
Aug  1 00:00:27 dnsmasq[268]: read /etc/hosts - 6 addresses
Aug  1 00:00:27 dnsmasq[268]: using nameserver 2a01:670:6a53:5f00::2#53
Aug  1 00:00:27 dnsmasq[268]: using nameserver 192.168.1.2#53
Aug  1 00:00:27 wan: finish adding multi routes
Aug  1 00:00:27 ntp: start NTP update
Mar  6 00:09:32 rc_service: ntp 433:notify_rc restart_upnp

A few versions ago RA was still working (maybe .53 or .54?) so I'm not sure what changed. If someone can let me know how to downgrade firmware I can try to pinpoint which release broke it for me.

Any thoughts on what could be wrong?

 

[Yggdrasil]

I managed to resolve this by factory-resetting the router and manually configuring it, instead of restoring a backed-up config.

It's been years since I've had to do that but I guess some cruft does build up from years of upgrades. In any case, I'm happy to be back on IPv6.