Streams and Logstash input plugins

I cannot get the Stream to work with logstash (v7.17 or v8.5).
My logstash input is
http {
type => “auth0”
port => 9090
ssl => true
ssl_certificate => “/etc/ssl/certs/”
ssl_key => “/etc/ssl/private/”
codec => “json”
tags => [“auth0”]
Verified this works fine by successfully accessing, get a simple page that says OK. The cert installed is a wildcard cert that matches the FQDN used so there are no cert errors.
In the Webhook Stream setup, the only value configured is Payload URL with
I run a tcpdump on the logstash server. I see the following.
syn from auth0
syn-ack from logstash
ack from logstash
ack from logstash
fin from logstash
fin ack from auth0
The only (unhelpful) message in Auth0 is Error “message”: “Could not reach endpoint”.
To me, logstash is clearly being reached, is responding with an ack, but never receives further communication from auth0 so logstash closes the tcp session.

I started with a username and password on the http listener, same story. Now I am no authentication.
At this point I have no useful logs to troubleshoot with, nor can I find anything from others having the same problem. Any ideas?