Enabling (and pinging) IPv6

I’m (still) very new to Qubes, so please be considerate. I’m using Qubes 4.0.4.
I’ve enabled (or so I thought) IPv6 support by running qvm-features sys-net ipv6 1 in dom0. I have sys-firewall using sys-net and sys-whonix using sys-firewall.
Furthermore, I have untrusted using sys-firewall and work using sys-whonix. In no qube, I seem to have proper IPv6 support - or so it seams: The command ping6 ipv6.google.com always fails with the error From fd09:<...> (<...>): icmp_seg=4 Destination unreachable: Address unreachable (for qubes using sys-whonix) or <...> icmp_seq=2 Destination unreachable: no route (for qubes using sys-firewall).
Interestingly, in the disposable whonix qube, I can access the site using the Tor browser (though I also can’t ping it).
What am I doing wrong?
Please let me know if I can provide further helpful information.