A port is just a magic number. It doesn’t correspond to a piece of hardware. The server opens a socket that ‘listens’ at port 80 and ‘accepts’ new connections from that socket. Each new connection is represented by a new socket whose local port is also port 80, but whose remote IP:port is as per the client who connected. So they don’t get mixed up. You therefore don’t need multiple IP addresses or even multiple ports at the server end.