This problem has been around forever, Linux seems to think it is fine to use the r8169 driver for an r8168 NIC but this often causes problems including the link not working at all.
In my case ethttool shows the link up and detected but it simply does not work especially on a laptop that has been resumed from suspension. Sometimes it takes several minutes for it to work or to unplug and replug the ethernet.
Here is the solution:
Install th........
CPanel says you can access 98% of the functions through CLI which experienced Unix/Linux admins prefer for simplicity and for scripting. I've never found CPanel easy to use from the admin panel, it seems everything is hard to find and a simple task becomes a series of hunts.
So for people like me here's the list: http://cpanel.net/system-administrators/command-line-scrip........
Even in new versions of Ubuntu this happens but for me I found out it was because of one feature under "Power Management".
I had "Spindown hard disks when possible" ticked, after disabling that, my computer wakes up from suspension every time now. So if your computer won't unsuspend with any version of Ubuntu/*Nix try disabling the spin down hard disk option as it's obviously the culprit for many situations.........