Material problem with imported FBX

Hello everyone!
I am facing this issue and can’t figure out the problem!
so, I have a 3d model (small city scene) which is made using 3ds max.
I exported fbx and imported in unity, after assigning all textures, I realized most of the scene is gray with no textures assigned.
Then i realized that a single material named “standard material” is responsible for the whole gray area.
As I tried to change the color of this material to red for example, the whole scene turns to red … (check the pictures)
I open the file with 3ds max and render, the scene is colorful …
First I need to understand something, that if the designer has used the same material in 3ds max with different colors(or textures) to each mesh , then why unity doesn’t support this? (check the material window picture snapshot)

There are not seperate materials for each mesh/model in unity , but I am able to see
what I want in 3ds max…
So the question is , if the designer has used the same material in 3ds max but changed material colors(or use of submaterials are not recognized by unity), will I face this problem in unity?
Does the designer have to redo the materialing and give a separate mat

You can use sub-object materials (like you did there) in Max and have it work just fine in Unity. But you have to make sure your export settings are correct to include material information. The FBX exporter (which is what you should be using) has a ton of options you have to get right.

Also make sure you use the latest FBX exporter plugin (download latest from Autodesk website).