I'm having the same problem on a new install of Armbian_5.35_Odroidc2_Debian_jessie_default_3.14.79 on an Odroid C2. Networking is fine on first boot, but after setting root password, creating new user, and reboot, eth0 doesn't connect.
Output from # armbianmonitor -U is here: http://sprunge.us/EOZQ
Output from # uname -a is this: Linux odroidc2 3.14.79-odroidc2 #4 SMP PREEMPT Wed Nov 22 16:09:18 CET 2017 aarch64 GNU/Linux
After quite a bit of fiddling using nmcli, renaming devices and connections, and several reboots, this seems to have resolved itself and it now connects and gets an IP via dhcp.
