I worked with .3ds too,
If there's texture mapping in 3dsMax, some triangles vertexes will brake in 3dsMax exports, because I think they are optimized for VBO or the old vertex buffer or something, where you have to index normal/vertex/texture coordinates in the same way, and texturing may brake triangles (the same vertex can have different texture coordinates on the different triangles). You wont recognize these braked vertexes in the 3dsMax itself.
By looking at your model, it seems a typical case, when the mesh has more polygons than vertices. (if they are shared)

If you create a 'geosphere' in 3dsMax, by default, it will have 320 polys, and 162 verts. (So more polygons!)
But you have a lot more vertices, than polygons.
So I guess I'm right.

I don't know how to overcome this, I think max has some logic in the indexing, but to puzzle it out how, pfff that's really hard.

I suggest you simply consider vertexes to be same, if their all coordinates are the same. (I think they should be precisely equal)

So find these somehow, than find the triangles they are on, find out the smoothing group ID of that triangle, than average those normals.

You don't have to do it realtime, calculate them at the beginning.