Comet GL-RM1 - tailscale fails to add IPv6 tailnet address to tailscale0 [1.8.0release3]

KVM
1

on a Comet GL-RM1, running FW 1.8.0release3

tailscale does not respond to requests sent via the node’s assigned IPv6 tailnet address

upon inspection:

“ifconfig tailscale0” shows only the link local inet6 address assigned to the interface:

tailscale0 Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:100.65.120.91  P-t-P:100.65.120.91  Mask:255.255.255.255
          inet6 addr: fe80::b787:96fc:6a2d:56a1/64 Scope:Link
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1280  Metric:1
          RX packets:23 errors:0 dropped:0 overruns:0 frame:0
          TX packets:17 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:1638 (1.5 KiB)  TX bytes:1964 (1.9 KiB)

and “tailscale netcheck” shows that it indeed did not assign an address:

Report:
        * Time: 2026-02-04T05:23:49.742153373Z
        * UDP: true
        * IPv4: yes, 71.68.32.131:44651
        * IPv6: no, but OS has support

after looking at the tailscale/tailscaled code, i think this is due to the fact that it’s failing to run the ip6tables binary when it’s doing its initial checks to make sure it can set up stateful filtering.

when attempting to run “ip6tables -S” which invokes the xtables-multi binary, we can see that this check (which the tailscale binary does to see if ip6tables is working) indeed returns a failed rc:

[root@patrick-kvm:/sys/module]# ip6tables -S
modprobe: can't change directory to '/lib/modules': No such file or directory
ip6tables v1.6.1: can't initialize ip6tables table `filter': Table does not exist (do you need to insmod?)
Perhaps ip6tables or your kernel needs to be upgraded.
[root@patrick-kvm:/sys/module]# echo $?
3

i can’t have IPv4 enabled on my tailnet due to conflicts with CGNAT, so i am completely unable to access my KVMs via tailscale until this is fixed.

2

Please try this firmware. It's based on 1.8.0 release 3 and adds support for ip6tables.

4

unfortunately that didn’t fix it:

Warning: client version "1.94.2-t0a29cf18b-g3f044c9f6" != tailscaled server version "1.92.5-dev20260203-te70c81e68-dirty"

Report:
        * Time: 2026-02-19T01:28:25.388343595Z
        * UDP: true
        * IPv4: yes, <hidden>:59917
        * IPv6: no, but OS has support

ip6tables runs now though, so it looks like the issue is deeper.

5

This firmware seems to have some bugs. When I enable Tailscale, for some reason, it deletes the default IPv6 route. Try adding the route using ip -6 route add default dev eth0 and then try again. It worked fine on my end after adding it.

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