Solve Ubuntu 14.04 LTS network suspending problem

To solve this problem, create a script file as bellow:

sudo gedit etc/pm/sleep.d/script.sh


With the following content:

#!/bin/sh

case "${1}" in
        resume|thaw)
        nmcli nm sleep false
                ;;
esac

Now make it executable:
sudo chmod +777 etc/pm/sleep.d/script.sh

 
It's done!

Tutorial extracted from http://askubuntu.com/questions/452826/wireless-networking-not-working-after-resume-in-ubuntu-14-04