Easy way to make my own Simple Master Server?

I want to make a simple master server that my clients can connect to. Quite a bit of data will be able to go through this connection, so they can chat with eachother or mail eachother whatever. This master will have its own database to store all the data I need.

Small Chat between players. Not big global chats, just private/group chats. Data holding vector3's to be loaded from the database and able to be requested/sent between players from the master.

When players actually get together and enter a game together, they will be put in a cloud sync room like photon or something of that sort. But all my saving/loading needs to go through the base connection to the master.

I have found some stuff on making a master server in unity, but nothing really aimed at what I'm trying to do, or giving me insight to do what I want to do. Kind of a book, but if anyone knows some framework that will do it or point me at some good stuff for writing my own I'd appreciate it.