Bug #9650


IPv6 connection drops (ir-)regular on Kabelvodafone (German cable ISP)...

Added by Ingo-Stefan Schilling almost 5 years ago.

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Background information
Kabel Vodafone is the successor of Kabeldeutschland, among other services they offer Business Cable access which I do use here, meaning: 1GBit down/50MBit up, 1x IPv4 fixed IP, IPv6 /56 network. Both IPv4/6 networks are handed over via DHCP. After some weeks of forth and back with Kabel Vodafone the delivery of IPv6 adresses/networks is working reliable, like clockwork on their side.

Since there are more and more pfSense users are telling they have the same issue, it seems there is a bug (in the constellation with Kabel Vodafone and IPv6/56) with pfSense, it seems obvious that on this side there might be in this constellation a problem.

  • Interface IPv4 (DHCP set, nothing else)
  • Interface IPv6 "Request a IPv6 prefix/information through the IPv4 connectivity link", "Send an IPv6 prefix hint to indicate the desired prefix size for delegation", "Start DHCP6 client in debug mode" and "dhcp6c will send a release to the ISP on exit, some ISPs then release the allocated address or prefix. This option prevents that signal ever being sent" are set, a "Prefix delegation size of 56" as well and everything else not except for block private and bogon networks, of course.

The issue
In my case from time to time (sometimes hours, sometimes days / weeks), pfSense seems to lose its standard IPv6 gateway and hence the whole IPv6 traffic is lost. IPv4 is still working as expected and not influenced by this behavior.

The workaround that helps me and some where I asked to try it is
See [Native-IPv6-with-dhcp6 from netgate forum []] exactly " Jeff V. Jun 18, 2014, 1:40 AM" wrote good news / bad news :)

For me and some others I contacted via Kabel Vodafone forum, adding the 2nd part of his interface settings in /var/etc/dhcp6c_wan.conf, meaning the

id-assoc pd 0 {
prefix-interface <LAN interface here> {
sla-id 0;
sla-len 8;

part plus running afterwards "/usr/local/sbin/dhcp6c -d -c /var/etc/dhcp6c_wan.conf -p /var/run/ -f -D <WAN interface here>"

does the job, pfSense behaves again as expected.


Not always but also it works to just dhcp6c -d... and not adding the id-assoc part in the settings (which does from my understanding and in my configuration > with LAN is configured with fixed IPv4 and IPv6 interface make no sense)

Perhaps it is just configuration - but it seems to me like a bug (which is why I made the priority Normal instead of High for now).

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