The goal of P2P Remote Desktop is to be portable, cross-platform and require no configuration for it to work. This is achievable through UDT Rendezvous connections and the STUN server. However, in some restrictive NAT environments, WAN connections may not be possible. You can read more about it here.

I developed 15 years ago the portable advanced remote administration tool called Pocket RDS for Windows and JRDS for cross-platform use.

Pocket RDS/JRDS utilize a reverse connection for direct client-server communication. To establish the connection between the client and server using reverse connection, you'll need to set up port forwarding on your router. Here's a helpful video guide to walk you through the process.

You can download and try them from here

Impressively, the remote desktop quality and speed seems faster than AnyDesk and TeamViewer! You can see a demonstration in this video

I'm considering also to making them open source too in the future.