IPv4 and IPv6 Dual Stack Does Not work when instance is not assigned public IPv4 address

[Sargun]

With the following cloud-init configuration:
system_info:
  network:
    renderers: ['netplan', 'eni', 'sysconfig']

network:
  version: 2
  ethernets:
    id0:
        match:
            name: e*
        dhcp4: true
        dhcp6: true

with version 17.1-18-gd4f70470-0ubuntu1 on ami-36a8754c, it writes out the following network configuration:
# This file is generated from information provided by
# the datasource. Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    version: 2
    ethernets:
        ens3:
            dhcp6: true
            match:
                macaddress: 02:14:13:66:8a:66
            set-name: ens3

----

This instance is in a (default) VPC with a private IPv4 address and no public IPv4 addresses.

[Joshua Powers (powersj)]

Think you hit submit twice, so marking as a dup of bug 1728152