Personal Firewall, Network Firewall, or Router
On your router, wireless router, cable modem, or firewall there may be specific settings to support port mapping and NAT port mapping. Often if these are not set then computers sharing the Internet connection on your LAN will not be able to access those services online.
If you have a single computer connected directly to a router or cable modem, restricting access may involve configuring the router or modem, or you could use a personal firewall on the computer to restrict access. Most personal firewall software will allow you to block outbound Internet access to specific applications and their respective ports, although the main focus of such software is to stop access from the Internet to the computer. If the PC firewall software is designed to route local network computers and devices to the Internet and use NAT, there will be varied and effective ways to restrict access to games, instant messaging, chat, and video and streaming audio applications.
This sort of outbound port blocking is not guaranteed on DSL modems, cable modems, or wireless routers or switches, but is very often included in Wireless Internet Access routers and switches with routing designed to share Internet access.