So I have investigated more & it is because I am getting vertex indecies, while the set shade smooth is looking for edge verteciesindecies. In my case f.e. the edge between vertex 0 & 16 has an index of 0 and between 16 & 32 an index of 1. I was able to see this in the spreadshead window.
However if I take this selection from index & plug it into the "Set Shade Smooth" Node and see which edges are being marked as sharp in the spreadsheet window. It will take every 16th edge.
I mean it is logical and is probably on purpose, it was just not clear, that the viewnode shows the vertex indecies & there is no conversion/transfer from vertex indecies to edge indecies.
However knowing that I was able to select the loops. Here is an example for those interested. My topology is 16x72, 72 is the amount of edges of my circle and the order of the idexes is 0 to 71 for the first loop.
Take two compare nodes, one where you compare the index to bigger 0 and the other to less 71. That's your range. Build in a multiply that enables me to select any edge loops out of the 16 that go along the mesh.
