Thank You for your reply.

I will try an even smaller time step (1e-04?)

As i need the interaction in my case i cannot use just the dpm model.

I tried everything i could with new boundary conditions and they should be fine, the mesh quality is good aswell.

My simulation ran once for 50iterations with first oder discretization, but when i tried second order momentum etc. it diverged and the AMG Error occured again.