Many to Many Video Chat/IM Client/Server/Central Server Application for Windows

I am looking to create a client/server/central server multi-party many to many video chat application that will include an instant messaging system and the ability to transfer files between users as well. I would need the ability to have registration of new accounts via the client as well as a website. I would like there to be a section on the client that will have rooms that can be created on the server or website that will allow multiple users to join and broadcast video. I would like audio to be available inside the rooms as well. I also would like some ability to have the users control the rooms via user types, like an owner, operator and friend of the room. I would like the project to be built in a .NET framework if possible. I also want it to be eventually supported on MacOS and Linux, so if that helps determine the language to use, then use that as a factor.