LAN clients cannot use IPv6 after some time

  • I´ve experiencing a strange behavior regarding IPv6 traffic. After some time (not measured exactly, but could be one hour or less) LAN clients cannot use IPv6 anymore. I´ve testing continuous pinging an outside server (ie the internet) and after some time the is no ping reply anymore. Saving and applying the LAN oder WAN interface settings on the PFsense box makes the ping and IPv6 as a whole running again for some time. IPv6 traffic inside LAN is not affacted as it does not pass the PFsense box.

    I experienced this behavior already under PFsense 2.3.x but didn´t have the time to investigate back then. Today I upgraded the PFsense box to 2.4.1 release and the behaviour is the same. We are connected to the Internet through a Vodafone cable connection. On the WAN side the PFsense is set to DHCP resp. DHCPv6. The LAN interface is set to Track Interface (WAN) for IPv6.

    DHCPv6 is enabled for LAN. RA is set to Managed with Router Priority High. Setting it to Assisted and/or Unmanged does not make any difference regarding the mentioned problem.

    While IPv6 is down for LAN clients the PFsense box itself could ping outside IPv6 adresses.

  • Is Vodafone routing you a /64, /60 or /56 subnet for your LAN clients? If you are not using the correct range you will not be able to contact addresses outside of your LAN as those addresses won't be routed to you.

    If you give me some more specifics on the addresses that you have routed to your device for your LAN network and the public IPv6 address you have assigned to your WAN interface then I can try to assist further.


  • Dear James,
    I get a /64 subnet routed by Vodafone. Besides this I get an single /128 address which is for the WAN interface itself. IPv6 is working for some time fine as stated above. But after some time is passed by no IPv6-traffic is being routed by the Sense unless you save and apply the settings of the LAN or the WAN interface. I believe some service is being restarted when doing so and this makes routing IPv6 traffic starting again for some time.

    Here are my settings: WAN and Interfaces-Summary.

  • I have the same problem! Also see my thread in the german section:ärlicher-packetloss-nur-bei-ipv6

    In my case it helped to disable the "Block Bogons" rule on WAN. I use a Dualstack Unitymedia Cable connection and they are providing me a dynamic /56 prefix.

  • Unfortunately since today even with allowed bogons it doesn‘t wirk any more. Extreme packetloss on IPv6 for the clients. The pfSense itself is running fine with IPv6 :(

    I don‘t know why this happens but it sucks. IPv6 is unusable for me with this problem.

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  • Nothing new here? Am I the only one with these strange things happening?

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