Why doesn't native implementation of UDP Hole Punching work?

Question

UDP

My implementation of UDP hole punching does not want to work.
Participants:
Server (public)
Client 1 (behind NAT)
Client 2 (behind NAT)
How I do:
1) Client 1 asks the Server for a direct connection with Client 2. (they are already connected to it via TCP)
2) The Server commands to connect to both , using UDP, to it. Fixes the remote addresses of both UDP connections.
3) The server sends a command to Client 2 to accept the UDP connection. (At the same time, Client 2 also receives the address of Client 1. To which it sends the packet in order to create a temporary rule on the router
) 1) to Client 2.
I write everywhere UDP connection, tk. I use a software add-on of a reliable UDP connection. (Lidgren.Network)

Answer 1

You seem to have the wrong protocol.
www.brynosaurus.com/pub/net/p2pnat

Answer 2

habrahabr.ru/post/142858
Below is a link to the library