I just had the same problem...
I installed Ubuntu server 17.10 on a freshly formatted disk. During the
install I was asked to configure the wired interface. Ok
After that I installed the meta-package ubuntu-desktop and re-booted. No
wired interface available in NetworkManager. Wireless is ok.
I had to change "/etc/netplan/01-netcfg.yaml" from:
# This file describes the network interfaces available on your system
# For more information, see netplan(5).
# Let NetworkManager manage all devices on this system
All is well after a reboot.
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No network connectivity (NIC unmanaged) after upgrade
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