Do a search.
In principle it is like this.
3CX uses a web server, this web server will listen to all the IP's and specified ports.
There are some config files you can change (Ill have to come back to you on that but they are discussed on the forum).
If you can get away with one network card in the box I would do that.
It would be nice if 3CX could include a function to bind the app to one network card, but not sure if they will.