lan clients periodically drop ipv6 connectivity

jarmo

I have a somewhat similar issue in a sense that my LAN clients start losing ipv6 connectivity over time, while ipv4 connectivity is just fine. I have also noticed that my clients (with ip-6 privacy enabled) start having multiple ipv6 addresses with different prefixes but similar suffixes. This is part of the output of ip -6 neighbor:

2opq:abcd:xyzw:efgh:xxxx:xxxx:xxxx:xxxx dev wzzzz router FAILED 
2opq:abcd:urvt:jklm:xxxx:xxxx:xxxx:xxxx dev wzzzz lladdr whatever router REACHABLE

where the xxxx-parts are all the same.

After finding this thread, it occurred to me that perhaps the problem is the same: maybe the router tries to renew ipv6 lease, but is in fact just given a new one, and the lease it tried to renew is hanging around in the failed route.

My question is: what are the exact steps I can do to verify this issue?

gambit100

@jarmo I'm not quite sure how the lan clients get different prefixes although they will be different than your wan prefix. As far as I know, the ISPs only assign one prefix for lan usage so unless you are configuring your lan to subnet the prefix into multiple smaller networks, they should all have the same prefix.
If your lan is using SLAAC for IPv6 addresses, your clients will have multiple IPv6 addresses: an Ipv6 address, a "temporary" ipv6 address, and a link local ipv6 address. The routable lan IPv6 address should have the same prefix and different suffixes.
In my case, I found using "Diagnostics->Packet Capture" that my router was sending IPv6 renew requests to the ISP and never getting a response (as shown in my previous response). Once the ISP fixed the issue, I started seeing the rc.newwanipv6 entries in the system log.
My only suggestion is to try and use either Packet Capture or Wireshark to capture RA packets or the prefix delegation packets and see if they match what your clients are reporting.