[FS#964] odhcpdIPv6 node(Win 10) stops sending Router Solicitation but it still receives RAs from LEDE

[LEDE Bugs]

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FS#964 - odhcpdIPv6 node(Win 10) stops sending Router Solicitation but it still receives RAs from LEDE
User who did this - Hans Dedecker (dedeckeh)

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The odhcpd traces indicate the default IPv6 route on the router is expiring :

Fri Aug 18 14:29:38 2017 daemon.info odhcpd[835]: Raising SIGUSR1 due to default route change
Fri Aug 18 14:29:38 2017 daemon.info odhcpd[835]: Raising SIGUSR1 due to default route change
Fri Aug 18 14:29:39 2017 daemon.info odhcpd[835]: Using a RA lifetime of 0 seconds on br-lan

This results into a RA being sent to the lan with routerlifetime 0
Shortly after odhcpd is informed about a new default IPv6 route but with a small lifetime (which is confirmed ifstatus wan6):

Fri Aug 18 14:29:54 2017 daemon.info odhcpd[835]: Raising SIGUSR1 due to default route change
Fri Aug 18 14:29:54 2017 daemon.debug odhcpd[835]: Netlink newaddr 2a01:2000:2000:ed4f::1%pppoe-wan2
Fri Aug 18 14:29:54 2017 daemon.debug odhcpd[835]: Netlink newaddr 2a01:2000:2001:5c3::1%br-lan
Fri Aug 18 14:29:54 2017 daemon.info odhcpd[835]: Raising SIGUSR1 due to address change on br-lan
Fri Aug 18 14:29:54 2017 daemon.info odhcpd[835]: Raising SIGUSR1 due to default route change
Fri Aug 18 14:29:54 2017 daemon.info odhcpd[835]: Raising SIGUSR1 due to default route change
Fri Aug 18 14:29:55 2017 daemon.info odhcpd[835]: Using a RA lifetime of 237 seconds on br-lan

This behavior is unusual as the lifetime of the default IPv6 route is determined by the RA route lifetime received on the wan.

Are you able to sniff IPv6 packets on the wan (eg via tcpdump) ? I'm particular interested in the RA and DHCPv6 messages received on the PPP link 
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=964#comment3268