When transferring textures, Unity overlays only one, what's the problem?

Question

Unity

Good day.
Faced such a problem. When importing a model (pre-modeled in Blender) into Unity and applying subsequent textures, the engine applies one texture to the entire object. UV unwrapping is done, each so-called wall is in Blender under its own texture, but Unity imposes only one texture on the entire, again, object. Assigned a separate material to each wall in Blender, thought it would help, but nothing. If anyone has any solutions, please share, I will be grateful.