After considerable manipulation a 4 hole Scherk2 surface was created from the basic uv curves.
Only one quadrant of open curves was used. The ends were connected with a through point curve, and then mirror and revolve to get 4 sets.
The through point curves were blended 4 times, and the 8 curves joined. Then network worked quickly. A 3 point circle trimmed the rounded ends.
Vertical copy and revolve of the surface enabled join to work.