When I go into the network settings in Ubuntu Gnome 14.10 (Which I heard is now a official flavour of Ubuntu) it usually says it's connected but at 10Mbs which is extremely slow and barely scratches the surface of my 30Mbs speed. I know my Ethernet card is capable of connecting up to 1Gbs! When I turn off the Ethernet and turn it back on, it just puts it back at 10Mbs! Once I unplug the cable and put it back in, it says "Cable Unplugged" when it's plugged in! My Ethernet card is a Realtek 8111 I think. Here is a pastebin for what is says for.
sudo lshw -C network