How do i block a computer which is on a network
To block the computer, you need to go to Internet> cable modem > my computer> network switch> computers. Select the computer that you want to block and save your settings. You can get detailed steps at http://esupport.trendmicro.com/solution/en-us/1038374.aspx.
Unplug the ethernet cable that is connecting the computer to the network. If it is connected wirelessly, then change the password in your router.