odhcpd does not advertise gateway #229
Description
I have three networks using VLANs that have nearly identical network and dhcp configurations. Only IP ranges vary. DHCPv4 works fine on all of them. DHCPv6 only works on two of them, one does not work for unknown reasons. After rebooting the router, it works for some time, after an hour or so the Windows machines on the affected network start loosing their IPv6 default gateway. It looks like odhcpd stops to advertise the IPv6 gateway information for this single network. I cannot see any details in the logs, even with loglevel 7 nothing helpful is shown.
Any ideas on this?
I know that IPv6 worked fine some month ago but I did not monitor it. No configuration changes were made at network or dhcp settings in the last few month. Using an old config backup from summer last year did not help. I am using a custom build with a custom dnsmasq build (without IPv6 support but with ipset) and a single patch that revers a single commit on thermal configuration.
Resetting the network stack on Windows without success. Several devices are affected, they all use DHCPv6, get an IPv6 address but no default route. SLAAC on Samsung cellphone works fine.
network:
43 config device
44 option name 'br-lan'
45 option type 'bridge'
46 option igmp_snooping '1'
47 option ipv6 '1'
48 list ports 'br-eth0.1'
49
50 config interface 'lan'
51 option device 'br-lan'
52 option proto 'static'
53 option metric '1'
54 list ipaddr '192.168.178.1/23'
55 list ip6addr 'fd2b:43d7:e9a:b2::1/64'
56 option ip6prefix 'fd2b:43d7:e9a:b2::/64'
57 option delegate '0'
58
dhcp:
38 config dhcp 'lan'
39 option instance 'lan_dns'
40 option interface 'lan'
41 option start '356'
42 option limit '100'
43 option leasetime '168h'
44 option force '1'
45 option ra 'server'
46 option dhcpv6_hostidlength '64'
47 option ra_default '2'
48 option ra_mtu '1492'
49 list ra_flags 'managed-config'
50 list ra_flags 'other-config'
51 list dhcp_option '6,192.168.178.1,192.168.178.1'
52 list dhcp_option '42,192.168.178.1'
53 list dhcp_option '44'
54 list dhcp_option '15,lan'
55 list dhcp_option '119,lan'
56 list domain 'lan'
57 option dhcpv6 'server'
58 list ntp 'fd2b:43d7:e9a:b2::1'
59 list dns 'fd2b:43d7:e9a:b2::1'
60 option preferred_lifetime '7d'
61 option ra_useleasetime '1'
62 option ra_preference 'high'
63
181 config odhcpd 'odhcpd'
182 option maindhcp '0'
183 option hostsfile '/tmp/hosts/odhcpd.hosts'
184 option leasefile '/opt/data/odhcpd.leases'
185 option leasetrigger '/usr/sbin/odhcpd-update'
186 option loglevel '4'
187
Also reported here: openwrt/openwrt#17636