server wont connect to network; cannot find device eth0

I suggest that you edit the file /etc/network/interfaces to replace the eth0 entry with wlp3s0 and add the SSID and encryption details, like this:

auto lo
iface lo inet loopback

auto wlp3s0
iface wlp3s0 inet dhcp
wpa-ssid <your_router>
wpa-psk <your_wpa_key>

So that you can ssh and ftp into it, I actually recommend a static address, not DHCP, however, let's get connected first and then proceed.

Reboot and tell us if you are connected:

ping -c3 www.ubuntu.com

EDIT:

If you wish to use ethernet as you indicated in your comments, then the sequence is:

auto lo
iface lo inet loopback

auto enp2s0f0
iface enp2s0f0 inet dhcp

Reboot.