Hi Stever!

A quick suggestion from me is to use more rounded (if not oval) shapes for the last end profile rings.
Maybe use a more transitioned shape for the next-to-last rings. The rounded shapes help prepare the surfaces to meet at the center more at the same time.
Or in other words, the corners of the more squarish shapes as they near the polar ends of the Network object will make for bad creases.

Also, make sure that the Network rail curves at the ends have the last two control points all exactly tangent, so that the ends are made flat.



These checks helped to make a smoother Network surface end when I tried it. (shown in pic)

Good luck.