But still the link to Podcast URL still does not work.
Google Search 'change "Podcast Library URL"' give some insight available at Apple Discussion Forum
The key message copied here:
Check /Library/PodcastProducer/Shared/Server/member_preferences_
There should be entries for server_host, tunnel_agent_host & tunnel_server_host that will need to be updated while PCP2 is shut down, which should handle it.
It works!