How to use a sphere or box reflection?

I currently have some sphere reflections in my game, but they leak a lot of light through my static meshes because they also affect areas outside of the room I placed them in.

How can I make it so that a sphere/box reflection only reflects within a box area?

The box reflection doesn’t work for some reason, it literally doesn’t change anything.

Well I’m not to sure but if light leaks through it because of your light map is incorrect.

No, the lightmap is correct, the reflections leak through because their box extends through the mesh. What my question is is how can I make a reflection only work within a specified rectangular room?