Docker 404 during apt get update

Problem:

During build of ubuntu images, apt-get can't resolve any archives (404's or 'Cannot initiate the connection').

Solution:

The issue is caused by the docker bridge hanging, so try the following:
sudo apt-get install bridge-utils
pkill docker
iptables -t nat -F
ifconfig docker0 down
brctl delbr docker0
sudo service docker restart