Ubuntu 14.04 to 16.04 upgrade – Network fix

If after a upgrade from Ubuntu 14.04 to 16.04 you notice that networking did not come back online please reference the steps below:

1. systemctl enable systemd-networkd
2. systemctl enable systemd-resolved
3. systemctl start systemd-resolved
4. rm /etc/resolv.conf
5. ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
6. vi /etc/systemd/network/20-dhcp.network 
7. Add the following:

[Match]
Name=e*

[Network]
DHCP=yes

After this is completed restart the server and networking should be back online.

If it did not come back online after this run
ifconfig -a

This will determine if your interface name has changed from eth0 to something else. If this is the case then you will also need to edit /etc/network/interfaces and replace references to eth0 with the new name.