Light bleeding through walls

Hi! I have the problem that you can see at the photo (I put a light to maximize the effect). When a dark room is near a very iluminated room (or exterior), there are a lot of light bleeding. How can I fix it? The rooms are builded in 3dsmax, trying to align vertex and aplying a UVW map box 1x1x1 meter. The lightmap is huge (is in orange at lightmap density). Do you know what I’m doing wrong? Thank you

I tried to weld all vertex between that separates both rooms, meet in the corners, créate manually the Unwrap instead of aplying the 1x1x1 UVMap, etc. The mesh, looking from above, is like this