How to make a network connection (non-RAS) available not to all LOCAL users?

Question

Computer networks

Network configuration: 3 computers are connected to the multiport router, 2 via Ethernet, 1 via Wi-Fi. The router raises the Internet via PPPoE and distributes it to all computers.
Each computer has a connection associated with a network card or Wi-Fi adapter. Through this connection there is a connection with the router and between computers. The goal is to deny selected local user accounts access to this connection. All this must be done on Windows XP. This must be done on at least one computer out of three, then I myself will figure out how to do the same on the rest.

Answer 1

windows xp? windows xp firewall? After these things, I think very few people will offer anything.