That is by design. The server that the report is going to does not contain any browse able content. To help people who see the hostname in logs, visiting the site redirects you to the parent site.
The fact that you can connect to the site with a browser, suggests that this is not a network issue. Most likely a firewall of sorts is preventing Duplicati from connecting. If the firewall is per-process, you will have no problems with a browser or a ping tool.
You see the warning, so clearly it is logged? Where did you expect it to be logged?
Duplicati has a usage reporter that sends anonymous usage stats back. You can see the data here:
https://usage-reporter.duplicati.com
However, this is NOT related to the ingress endpoint you mentioned. That endpoint is for the Duplicati console/portal that has a manual setup step.