IPv6 relay cannot discover LAN device, Bad file descriptor sending to wan@pppoe-wan

Device Version:

OpenWrt 22.03.2
odhcpd-ipv6only 2022-03-22-860ca900-1
odhcp6c 2022-08-05-7d21e8d8-18

Description

After pppoe reconnection, the IPv6-PD prefix is no longer issued, only a /64 address is issued at pppoe-wan, and none of the LAN devices have IPv6 addresses.

After trying with the relay method (see config file below), I can get the address assigned, but the OpenWrt log keeps reporting errors and the LAN devices cannot access any ipv6 site.

Syslog:

odhcpd[1605]: setsockopt(PACKET_ADD_MEMBERSHIP): Invalid argument
odhcpd[1605]: Failed to send to 240e:xxx%wan@pppoe-wan (Bad file descriptor)

/etc/config/dhcp

config dhcp 'lan'
    option interface 'lan'
    option start '100'
    option limit '150'
    option leasetime '12h'
    option dhcpv4 'server'
    option ra 'relay'
    option ndp 'relay'
    option dhcpv6 'relay'

config dhcp 'wan'
    option interface 'wan'
    option ignore '1'
    option master '1'
    option ra 'relay'
    option ndp 'relay'
    option dhcpv6 'relay'

Temporary Solution

I ping6 the router on a LAN device and I can access v6 sites. To Solve the problem automatically I added script

#!/bin/sh
[ "$1" = "pppoe-wan" ] || exit 0
ip -6 route add default dev br-lan table 6
ip -6 rule add iif $1 lookup 6

Is this a bug of odhcpd-ipv6only?

VLAN

I set up my pppoe-wan interface on an VLAN device wan.2. I don't know if VLAN will affect odhcpd. /etc/config/network

config interface 'wan'
    option proto 'pppoe'
    option ipv6 'auto'
    option username 'xxx'
    option password 'xxx'
    option device 'wan.2'
    option ip6assign '64'

config device
    option type '8021q'
    option ifname 'wan'
    option vid '2'
    option name 'wan.2'

Chinese Ver. https://www.v2ex.com/t/903292

openwrt / odhcpd