Turn on the multiple remote computers with Latch.
No need to open ports on the router.
No need to open ports on the firewall.
Easy and cheap.

INSTALATION MANUAL

We will install the download manager wget to get the plugin and also python 3.0: 
>sudo su 
#apt-get install wget 
#apt-get install python3 

We will enter the installation directory “/usr/local/src” and download our plugin: 
#cd /usr/local/src 
#wget https://github.com/maxssestepa/Latchwake/archive/master.zip  

We will unzip the downloaded file and rename the directory as "latchwake". Remember that the files in this directory have to belong to the user "root" to ensure the safety of the plugin: 
#unzip master.zip 
#mv Latchwake-master latchwake 

We adapt the appropriate user and permissions: 
#cd latchwake 
#chown root.root * 
#chmod 550 latchwake latchwakeon.py install.py 

We will enter the latchwake plugin directory and execute the plugin “install” command: 
#./install

Detailed manual:
https://drive.google.com/file/d/0B1VM3nUrISLZZE9MVmEzVUFPdHM/view?usp=sharing