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

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - forfree (freefor) 

Attached to Project - LEDE Project
Summary - odhcpdIPv6 node(Win 10) stops sending Router Solicitation but it still receives RAs from LEDE
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - High
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Router: Buffalo wbmr-hp-g300h
Lede version: Reboot (SNAPSHOT, r4696-df3295f50e)
ISP: TIM Italy - ADSL2+
NIC: Realtek PCIe GBE - Driver 10.19.627.2017 (27/06/2017 - Latest)

I have set up a new pppoe session to get IPv6 on all my mobile devices(see attachment). Without a dedicated pppoe session,
my Android phone could not reach IPv4-only hosts.

Note:My ISP delegates via DHCPv6-PD a single dynamic /64.

Problem:

Everything worked fine until I noticed that my Windows 10 (Build 15063.540) laptop loses its IPv6 default gateway after 3 hours
more or less. If I disable/reenable the NIC (wired) the default gateway returns and I can use IPv6.

I did a wireshark capture on my laptop and I can see my laptop receiving RAs but I stop sending RS to the router.
I captured at the same time traffic on the router and indeed there are no RS from my laptop.


I attach here the output before and after I have a default gateway for IPv6
 - ifstatus wan
 - ifstatus wan6
 - ifstatus lan
 - ubus call network.interface.wan6 status

You can find also my /etc/config/network, /etc/config/firewall and /etc/config/dhcp settings.

Let me know if you need more logs. 
I can easily reproduce this problem(just have to wait 3 hours).
 
Forum discussion: https://forum.lede-project.org/t/problem-with-ipv6-and-mobile-device/241

One or more files have been attached.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=964