How to make a modem connection only for a specific user?

Question

Computer networks

Good afternoon. There are two users on one computer who are connected to the Internet via a cable. There is also a 3g modem. How can I make sure that when one user connects to the Internet via a modem, the second one continues to use the cable?

Answer 1

Theoretically, it is required to write a bat-file that activates the Internet connection when the user logs in. For each user, specify the required.
Practically two users work at the same time on one computer?