I need to know what jammer would be useful. 

I need to know what product would be useful.

There is a 4G EE antenna/aerial on the exterior of the garage which has a sim in it and picks up signal from a mast and connects to a router within the garage to provide broadband. The garage is across the garden 15metres from the my main building where I would like to install a device to have some control over a youngsters use of this equipment.

What could be used to jam either that signal or the wifi please?