Wireless networking not working after resume in Ubuntu 14.04

Solution 1:

The above answers did not work for me on 14.10. After a bit of trial-and-error, I ended up with this,

#!/bin/sh

case "${1}" in
  resume|thaw)
    nmcli r wifi off && nmcli r wifi on ;;
esac

Put this in /etc/pm/sleep.d/10_resume_wifi
Make it executable sudo chmod 755 /etc/pm/sleep.d/10_resume_wifi and the problem should be fixed immediately.

Solution 2:

I got a solution but it is just for restarting your network manager.

sudo service network-manager restart

It is not the permanent solution.