I have exactly the same problem at Hetzner from a dedicated server, so the problem is definitely related to TrueNAS-SCALE !
I did several searches there, until helping me with Webmin, I managed to make the IPV6 work by manually adding a Default IPv6 Route of the server.
By comparing from another Hetzner server with an IPV6 which pings outwards, I think I have put my finger on the problem, TrueNAS-SCALE seems to be creating an IPv6 Route by default, but on the "lo" interface !
The IPV6 gateway is obviously defined in TrueNAS-SCALE, but it attaches to the wrong interface.
By issuing this command:
Code:
ip -6 route add default via fe80::1 dev enp3s0
I have instead of the "lo" interface the "enp3s0" interface and it pings !
Waiting for a next correction, I defined this route in Webmin.