Ok, just spent the day installing ubuntu server over and over to see what happens with this and that.

I tried a few options for correcting the problem:
1) Edit connections >>> delete whatever connection is listed, create / add new connection ... I tried that, but it had no effect at all, rebooted, still no effect.
2) In terminal >>> sudo service network-manager stop && sudo rm /var/lib/NetworkManager/NetworkManager.state && sudo service network-manager start >>> reboot ... no effect
3) Uninstall libglib2.0-0 >>> reinstall libglib2.0-0 >>> it broke my server >>> reinstalled
4) Uninstalling and then re-installing the network-manager - no effect.

I then recalled that during the setup and install of ubuntu server, it asks which ethernet port (I have two onboard gblans) is primary, I chose eth0, but, it appears I was plugged into eth1 with the ethernet cable >>> I changed the cable to the other port et voila!! - all better instantly, connection manager recognized that I was plugged in and showed all appropriate info in the Connection Information window.

So, no guarantee, but perhaps you have a similar situation with which port you're connecting the ethernet cable to when there's only one cable connected - worth checking out.

Cheers.