Comment 27 for bug 1636912

For the record: the "hang" was the ~ 10s timeout for IPv6 RA. I was testing with Yakkety/Zesty's QEMU whose "user" net has a builtin RA (you get an fec0::* address), while xenial's doesn't.

We enable RA (on the client side) by default, and IMHO should really do so -- selling a new solution in 2016 which does not speak IPv6 would be hilarious. You can't also significantly reduce the timeout, as this would make RA unreliable and it's presumably also a specification somewhere.

So AFAICS the remaining issue is just to make networkd run before dbus.service/socket in systemd, and add "After=networking.service systemd-networkd-wait-online.service" and drop "Wants=networking.service" in cloud-init.service.