Dotted blimps on parts edges

Hi all,

I am working on my first blender project and found a problem during my render runs. There is always a “dotted” line of reflections on some parts’ edges (see attached screen shot). How to reduce that? Is it just a question of playing around with lighting or do I have to change the material settings (perhaps “sharpen” the edges because I improved all parts previously by multiresolution modifier)?
Many thanks in advance for your support.
Kind regards