The problem I had was that wired connection works after a cold boot, but not after a suspend or hibernate.
The network driver (alx) has a known issue, but the fixes presented elsewhere did not work, although removing and readding the alx module manually ffixes the problem. Thanks go to http://ubuntuforums.org/showthread.php?t=2128766 for the initial idea.
Environment: Ubuntu 13.04 unity desktop on a Toshiba P870 with SSD
Workaround: Removing and then adding the alx module back with a few seconds delay. One second is sufficient for my Core i7 system booting from SSD, but I expect that to vary. I left the remove module command in for when the system is being suspended, although it isn't nessisary for my system.
If someone can come up with a neater solution, I would be interested, but this got me going.
Code:#!/bin/sh # Fix Toshiba P870 "network disabled after suspend" issue. # Problem in atheros network driver (alx for eth0). case $1 in suspend|suspend_hybrid|hibernate) modprobe -r alx ;; resume|thaw) ( sleep 2 modprobe -r alx modprobe alx ) & ;; esac