Comment 9 for bug 1574844

I can confirm the issue most commonly happens with the first or second machine in any given model, including the admin (controller) model, provided there is some delay between adding the model and deploying 2 units e.g.

juju add-model foo && sleep 3 && juju deploy -m foo ubuntu -n 2

is usually (80% of the time) sufficient to reproduce the issue consistently for machine-1 in the model foo.

Also, watching `lxc list juju-<model-uuid-prefix>` as containers start I can see 100% of the time when the issue appears, the IPv6 address of the container appears before the IPv4 address. After a few seconds, both addresses appear.