This is very useful post because when you are going to run the application with Centralized DB you have to give the privileges to the other computers to access Single database hosted in your LAN.
So what you need to do is just run the single database in one computer then go to MySQL console and type the following commands
mysql> grant all privileges on *.* to 'root'@'%' identified by 'root_password'; mysql> flush privileges;
By replacing the ‘%’ to any IP address you can grant for the given IP