Did you connect to the network?
sudo ifconfig -a
sudo dhclient eth0
That specific ubuntu image didn’t have connman installed by default to auto connect to the network.
I’ve got a newer version ubuntu that i’m slowly rolling out, just in the process of valding/updating all pages…
You can grab it here:
https://www.digikey.com/eewiki/display/linuxonarm/A10-OLinuXino-LIME#A10-OLinuXino-LIME-Ubuntu18.04LTS
Regards,