IPv6 suddenly stopped working

Installation
1

Hi there,

If anyone can help would be appreciated. I have all of a sudden lost IPv6 connectivity although it’s been running great for a few months. I can’t think of anything I’ve changed - all other clients on the same network have IPv6 and work flawlessly.

Any assistance would be greatly appreciated!

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2

When I add a new network interface, it gets picked and associated to the HassOS default network profile and instantly picks up IPv6 but then after restart, no network connectivity. Not sure what’s going on.

3

I see a fe80 address listed, so IPv6 seems to be there.
fe80 is a non-routable IPv6 address and the fe80 network will exist on all your interfaces, but it might not be the same fe80 network across the interfaces, so if you have multiple NICs in the HA server, then this might be the issue.

4

Maybe describe what you mean by lost IPv6 connectivity …
If you mean to say that you had non FE80:: addresses when only using enp3s0, then could be your home router or Thread Border router (on the same LAN as your enp3s0) stopped advertising the IPv6 prefix.

5

thanks for your responses - I should be getting a 2a02:… /64 address as I was before. every other client on the same network is getting it except home assistant (although this was working perfectly fine a few weeks ago); appreciate any insight in advance!

6

HAOS is really not that good with IPv6 configurations, so you might actually have a 2a02 address, but only the fe80 is shown and used.

7

If you can get back into your console:

  1. show which connection profiles you have, enter: nmcli con show
  2. See which ones are active, enter: nmcli con show --active
  3. for the ones that are active, see how the active profile’s “DEVICE” name compares to the ip interfaces, enter: ip addr . Also check to see if has a 2a02:: address.
    Ex. if “Supervisor enp3s0” profile is active, it’s device name is enp3s0, and so enp3s0 should show up in the response to the ip addr command.
  4. if #3 checks out OK, then the ipv6 variable/settings you provided above for “Supervisor enp3s0” should work.

The only thing that comes to mind as to why it is not working, is that your home-router (which appears to be advertising a prefix of 2a02:; since your other devices are getting it) is somehow not getting those prefix advertisements to your HA device. The advertisements are sent using an Ethernet multicast destination address. If you have layer2 switches that have IGMP/MLD snooping turned on, it is possible these switches are blocking these prefix advertisements.

8

thanks for this - all 4 check out OK. also checked out IGMP snooping being off (unifi network layer + opnsense routing). I’ll keep searching, your tips are helpful, thank you!

9

Another thing to check while in the HAOS console is:
cat /proc/sys/net/ipv6/conf/enp3s0/accept_ra_pinfo

This should return a 1.
If it returns 1, then next check
cat /proc/sys/net/ipv6/conf/enp3s0/autoconf
This should also return 1.

If either returns 0, then that would explain why prefix advertisements are not being accepted.

10

Thanks for the help. After updating to 2024.11.1, IPv6 is restored, thanks!!