When we switch to Server Type: Service in the Server Begin node, the ShotGrid nodes inside the block complain when cooking:
Error sharedserver name could not be found
This service does exist in the PDG Services tab, and it is running.
Seems to me that the ShotGrid node does not know how to find the service? And I couldn't find a setting on the node to tell it the name.
This is Houdini 20.0.590. Haven't tried 20.5 yet (because it does not work with the official ShotGrid integration [community.shotgridsoftware.com]).