There is a server with two network cards. Through the first server is connected to the Internet. This connection is shared by connecting to another computer (second network card) so that it also has access to the Internet (done like this: Control Panel \ Network and Internet \ Network Connections -> connection_ with provider => Properties -> Sharing -> Allow other network users to connect through this computer's Internet connection) The appropriate field indicates the name of the network connection that will access the Internet. Actually, the question is in the title.
PS: Maybe the question looks confusing, but I hope they understand me.
PS2: Yes, I understand that there are routers for such tasks. But the method without routers interests.