Comment 22 for bug 1510345

Some of the newest Amazon EC2 Published AMIs at [1], for example, ubuntu-wily-15.10-amd64-server-20151219 AMIs: ami-38796759 (us-west-2) & ami-94683ffe (us-east-1) only successfully boot for instance types that don't have enhanced networking enabled (http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking.html).

So attempting to launch a c4.xlarge for example will fail/hung with the following logged:

[ 63.181996] cloud-init[932]: ci-info: +++++++++++++++++++++++++++++++++++++++Net device info+++++++++++++++++++++++++++++++++++++++
[ 63.182482] cloud-init[932]: ci-info: +--------+-------+------------------------------+---------------+-------+-------------------+
[ 63.182886] cloud-init[932]: ci-info: | Device | Up | Address | Mask | Scope | Hw-Address |
[ 63.183281] cloud-init[932]: ci-info: +--------+-------+------------------------------+---------------+-------+-------------------+
[ 63.183664] cloud-init[932]: ci-info: | lo | True | 127.0.0.1 | 255.0.0.0 | . | . |
[ 63.184172] cloud-init[932]: ci-info: | lo | True | ::1/128 | . | host | . |
[ 63.184482] cloud-init[932]: ci-info: | lxcbr0 | True | 10.0.3.1 | 255.255.255.0 | . | 5a:27:38:06:7c:a3 |
[ 63.184871] cloud-init[932]: ci-info: | lxcbr0 | True | fe80::5827:38ff:fe06:7ca3/64 | . | link | 5a:27:38:06:7c:a3 |
[ 63.185163] cloud-init[932]: ci-info: | ens3 | False | . | . | . | 0a:f9:a1:59:f3:1b |
[ 63.185335] cloud-init[932]: ci-info: +--------+-------+------------------------------+---------------+-------+-------------------+
[ 63.185502] cloud-init[932]: ci-info: +++++++++++++++++++++++++++Route IPv4 info+++++++++++++++++++++++++++
[ 63.186068] cloud-init[932]: ci-info: +-------+-------------+---------+---------------+-----------+-------+
[ 63.186556] cloud-init[932]: ci-info: | Route | Destination | Gateway | Genmask | Interface | Flags |
[ 63.186997] cloud-init[932]: ci-info: +-------+-------------+---------+---------------+-----------+-------+
[ 63.187380] cloud-init[932]: ci-info: | 0 | 10.0.3.0 | 0.0.0.0 | 255.255.255.0 | lxcbr0 | U |
[ 63.187770] cloud-init[932]: ci-info: +-------+-------------+---------+---------------+-----------+-------+
[ 63.188186] cloud-init[932]: 2015-12-24 04:57:59,899 - url_helper.py[WARNING]: Calling 'http://169.254.169.254/2009-04-04/meta-data/instance-id' failed [0/120s]: request error [('Connection aborted.', OSError(101, 'Network is unreachable'))]

[1] http://cloud-images.ubuntu.com/releases/wily/release/