[saran k]

is there a software that can be used to disconnect internet connection on selected system on a lan

 

[caserta]

you can turn of ports via firewall....

 

[Fjandr]

The firmware on most consumer routers has limited access control capability. Usually, you will be limited to permanently denying a system based on its MAC address or you can limit connections based on the time of day.

You should refer to the manual for your router to determine the access control capabilities available to you.

If you'd like more help, please post the make and model of your router.