I am making a house in Blender 2.93.5, and so far it has over 1,500 objects and about 130 lights in all. It has multiple rooms, each with a separate set of lights each, and one large hall to connect them. I was about to install lights in the hall when a problem turned up.
When I went into rendered mode to see the hall without lights, I found it fairly bright with lights from behind the walls.
What I have attempted:
I have attempted many things to get the walls to block the light and the light to not shine through the walls, including adding solidify modifiers and things like that, but nothing worked. I have also combed through all related Blender stackexchange questions and answers, but none of them did any good at all and my problem still remains.
Cycles does not have this effect, but with all those lights it takes way too long to render anything, and as I hope to use this house for a video game I am developing, that would be extremely inconvenient. Basically, I'd like an answer for Eevee. I don't want to just switch to using Cycles.