Comment 68 for bug 927782

Follow up from #67 in response to #66.

Upgrading from 3.5.0-26 to 3.5.0-27 does NOT resolve the problem. ALX module is loaded OK, but plugging network cable is silently ignored (no dmesg activity, NM doesn't seem to notice anything).

After rmmod alx && modprobe alx the module is reloaded and dumps lots of garbage on dmesg. Network cable is detected but no packets go out or in.

Workaround is to:
# rm /lib/modules/3.5.0-27-generic/kernel/ubuntu/alx/alx.ko

then compile alx.ko from compat-wireless (I use 3.6.8-1-snpc) and make install. This puts alx.ko in /lib/modules/3.5.0-27-generic/update/drivers/net/ethernet/atheros/alx/alx.ko

After rebooting alx module works perfectly.

Given that the Ubuntu-provided alx module is so broken I suggest you remove it with a new kernel update, then fix it, TEST IT, and then include it in a future kernel version.