I am trying to create Client-Server connection network over android devices via blue-tooth(as the connection platform).One device acting as Server and other 4 or five devices as
First of all, you have to notice this library is for socket communication using RFCOMM protocol which is not Low Bluetooth https://en.wikipedia.org/wiki/List_of_Bluetooth_protocols
If you want help, I need more informations, as your android version, a piece of your code and your logs as well.
Moreover, you can see this library in work on this game https://play.google.com/store/apps/details?id=com.drgames.domino Using one server and 3 clients in bluetooth.