Need help with shader.

Hello friends! I just finished this base metal shader from the mailbox course, and I tried to follow along as close as possible. I am an utter noob when it comes to shaders and rendering so I can use some help here.

I might have made some mistakes along the way or maybe its because of new blender version. So please take a look at these screenshots and tell me how can I improve this to get  better results.  The vertex paint in dark areas is messy so ignore those areas.

The render is viewport render screenshot with 128 samples. Area light is set at 500W strength.