Multiplayer with C++ on many platforms

Hello all,

I am going to write a 3D app that will be using Networking/Replication. It will be running on server and available for many platforms. I mean clients on various platforms (Windows, Android, Mac, Linux, etc.) will be able to join the server online and do something. Is it possible? And how to do that in short. Can I write the app for server with Linux and other platforms will connect?

Thank you for any help!