How do I connect C# server-client program with deferent NAT table over the internet network?

See more:

C#

network

Internet

sockets

I want to run this [C# remote desktop program] or every simple C# Server-Client socket app over the internet network but it does not work on the internet network although it works on the LAN network because of the NAT table.
To solve this problem, Port Forwarding has been suggested, but doing this on a server-side router all the time is not at all interesting or commercial.
What can be done to solve this problem in similar commercial software such as AnyDesk or TeamViewer?
It is said that there is a method called NAT hole punching to solve the NAT table problem and make computers recognizable over the Internet.
Can this method be implemented on [this program] or other C# Socket Server-Client programs?
(For example, a very simple C# Socket Server -Client program for sending text)
Can anyone show me a coding example of NAT hole punching for a C# Socket Server-Client application or bring a resource to do this or something like that?
Thanks a lot.

What I have tried:

I'm still researching to find a way to connect computers on different LAN networks over the Internet with code example (like NAT hole punching) and I still can't find a practical example to test...
Thanks for guiding me.