Mobile networking

Hi everyone,
I am currently working on a simple mobile game about gomoku (strategy / logic game). I want to make a multiplayer in it, but I am not pretty sure, how to implement network in it. I read something about sessions via default subsystems, but there is no ideal step by step tutorial or full documentation how to set it up. I am in a situatuion, that players can either create a server in the game or look for running servers. Any ideas how to create this on android? I would be ok, if player would be able to send “strings” that would include some informations. The recieving client will know what to do with it. I know I can somehow use “open level” and type in IP addresses, but what if there would be more servers on one IP? For example on a school wifi system? And how would be player able to find some servers if he doesn’t know where to look? Any ideas?