I'm using a Gigabyte 990FXA-UD3 R5.

To get ethernet working on 16.04 server I just had to enable ioummu in the bios, and just set dhcp in /etc/network/interfaces.  

press f12 to open the guake terminal

type:

ifconfig -a

then press enter

This should list all your network interfaces.  If you are currently using wifi there are probably 3 listed.  Your ethernet, your wifi, and your loopback (lo).

Note the interface name that corresponds to your ethernet: lets call it "ethernet" for the following commands; just swap "ethernet" with this interface name.

type:

sudo ifconfig ethernet down

then enter:

 miner1

when prompted for the password

type:

sudo ifconfig ethernet up

then enter:

 miner1

when prompted for the password

if ethernet is still not working at this point try:

sudo ifup ethernet

then enter:

 miner1

when prompted for the password