I installed 16.04 over Windows today and everything is broken! My ethernet cable is my sole connection to the internet and it's just not working at all. It's a Realtek device with the default driver r8169. The thing is plugged in and it's detected by Ubuntu but my router doesn't see it at all. I've tried turning off the DHCP and set it static. I've tried restarting the network manager. I swapped the drivers to r8168 and that has just made things worse.
Any help would be appreciated! It's midnight here but I will respond back first thing in the morning! Thanks!