Screen sharing over internet using c#

Question

Anyone has any info how can I share my screen over internet. I am working in a remote desktop application.

I dont want to use any router port forwarding as that will not work for my application.

I use this code and its working nice if I am inside NAT / LAN. But how do I make it working over internet ?

From some research, I found that I possibly will have to have a server in the middle.

Customer PC (session code a1) <---->Server (a1) <----> Engineer PC (Session a1)

But how do I do that using c#.net ?