Why is static IPv6 pinging between LXC containers failing?

[reckless]

I have three containers, all on the same vmbr2 bridge. This bridge has an IP of fdac::10.

The LXC containers have static IPs of fdac::20, fdac::30 and fdac::40 and all of them are connected via vmbr2.


Yet somehow, the LXCs can't ping eachother. I'm running dual stack, and all IPv4 pings between containers and host work just fine, zero issues. I can also ping each container using IPv6 from my Windows workstation just fine, no issues. So why do the IPv6 pings fail between the LXC containers? Is there a setting I'm missing in Proxmox?

/etc/network/interfaces:

auto vmbr2
iface vmbr2 inet static
        address 192.168.1.2/24
        address fdac::10/64
        gateway 192.168.1.1
        gateway fe80::aaaa:bbbb:cccc:dddd
        bridge-ports bond0
        bridge-stp off
        bridge-fd 0
        mtu 9000