Prefix delegation on IPv6 drops out from time to time

Hi everyone,

I'm using OpenWrt 21.02.0 r16279-5cc0535800 on a Linksys router and I've set it up in such a way that at
IPv6 the PD mostly works. But then there are days like today
where my clients do not get a delegated IPv6 address.

I must then always on the router

uci commit network
/etc/init.d/network restart

execute so that the addresses are delegated. Does anyone have an idea with what
could this behavior be related?

Best regards


Does it happen at specific timecycles or randomly?
One thought is that the dhcp server is not replying to the solicitations properly, and the delegated prefix is retracted when the leasetime is over.
The only way I can think to troubleshoot that is to setup a packet capture, write the output on the device, and have a look at it when the problem occurs.
Does the problem fix itself if you run ifup wan6 ?

I'd say it's rather random as I've been able to SSH to my server over and over for days and those are just IPv6 addresses. I notice the absence of the delegated prefix when that no longer works.

You would have to watch that.

So far I have only implemented the above commands. I can test this next time.

Not really, you let it capture and when it happens you check the captured packets.

So the whole thing seems really shaky to me. The IPv6 addresses are regularly gone after a restart, the provider's IP address change and after a restart of the OpenVPN service.

I then have to do it regularly on the OpenWRT console:
uci commit network && /etc/init.d/network restart
In addition, I have to reload the network on the client:
systemctl restart networking.service
Only now can I use IPv6 connections again.
After each restart of the network settings, the VPN tunnel connection is also stopped. A restart via Luci or the console
/etc/init.d/openvpn restart
destroys the IPv6 connection again.
I can't find a solution at the moment, or with which filter could a capture be carried out here?

tcpdump -i <wan6 physical interface> -w /tmp/capture.pcap -evn udp port 547 or ip6[40] == 128