OpenVPN, what ports are used in client-client communication?

Question

openvpn

Hello.
There is 1 OpenVPN server and 2 clients.
We connect to the vpn server via an external ip + port 1001. The server sees all clients, ping, as well as clients see each other. The question is, if clients cling to the server on port 1001, and on what port do they see each other?
How do opwnvpn clients communicate with each other through an intermediate server?
That is, my task is:
1. Client No. 1 connects via port 10010 to Client No. 2, in windows I want to send client 1 to client 2 through Portproxy, but I don’t know which port to redirect: Client1 (port)> Client2 ( 10010).
PS I do not know how to formulate correctly, I hope they will understand me.