urlopen error [Errno 111] Connection refused while CURL works

Question

I have a splunk custom webhook action. The action python script seems to fail at this point

Error sending webhook request: <urlopen error [Errno 111] Connection refused>",

Executing a CURL command for the same POST request works well though.

Why would Splunk complain with Connection Refused when I can connect to that same request via CURL? Any thoughts?

Ta!