Help with weird lighting on objects placed outside

Hi,

could anyone help with a mesh, seems to happen to alot.

When the object is placed outside it has a high shine to it where i just want a completely Matte finish. Ive added blank spec and bump maps and it doesnt seem to change it.

Happy to provide the mesh.

Looks exactly how i want it to when viewing in S4S, not sure if its an issue with the base object im merging it from, what do most people use?

drive.google.com/drive/folders/1njf0WO2dNYTiPwOBdKTX15GQNS_Tdc9R?usp=sharing

Thanks