I'm running Ubuntu 12.04 x64 on an Acer Aspire One 722-BZ454. OS was installed a short few days ago. Yesterday, I unplugged the ethernet cable to take the netbook outside for a few hours. Came back in, plugged the ethernet in again, everything worked fine as normal. A couple hours later, I noticed horrible lag on my desktop, with nothing using data. Check the netbook, and see the connection is absolutely maxed out. Being hasty, I simply unplugged the ethernet cable and went about my business.
Some time later, I decided to plug it back in and see what was using all of that bandwidth, only to find that I could no longer get a wired connection. All configuration checks out, as far as I can tell, but Ubuntu just keeps trying to connect and failing, with the message:
Disconnected - you are now offline
I have a separate Windows 7 partition, and decided to see if the situation was any clearer over there, only to find that I cannot connect to the internet there, either. I CAN, however, still see all other devices (laptop, desktop, etc) on the network and access their shared files perfectly fine.
dmesg returns only:
[ 9.894869] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 27.871448] atl1c 0000:06:00.0: atl1c: eth0 NIC Link is UP<100 Mbps Full Duplex>