Blocking a device from sending DNS requests?

[itayt]

I'm trying to block a device from accessing the internet while retaining LAN access however its documentation says that if I only block access to WAN without blocking DNS requests, the device would be sitting in zombie state but I'm not sure how to achieve that in Merlin
I'm willing to use addons to achieve this if necessary (I currently have Yazfi and Skynet installed)

 

[Tech9]

I'm trying to block a device from accessing the internet

What about this?

Parental Controls, Time Scheduling - available in Asuswrt GUI.