Substrate Material and Specular Highlights

I created a simple Substrate Material. See nodes below.

When rendering with default Lumen, I am not getting any specular highlights.
When rendering with PathTracer it seems to be okay.

Question:
What do you need to change in the Substrate Material in order to see and also control the Specular Highlights when using Lumen?

Image below shows default Lumen, with no specular highlights:

Image below shows Specular highlights when using PathTracer.

Thx for any info, hint, tips and thoughts.

found the solution, posting here so it might help someone else in the future: