Comment 7 for bug 1311257

I have the same issue. Upgraded 12.04 to 14.04 on a Lenovo T530. Killing wpa_supplicant resolves the issue, so I wrote the following script which seems to work:

Put it in /etc/pm/sleep.d/wpa_supplicant_workaround :

#!/bin/sh

case "$1" in
  resume|thaw)
    killall wpa_supplicant
    ;;
esac

Not really ideal, but it saves a bit of typing at each resume.