WebRequest returns undocumented code 1009 with error 5203 for one domain only

Hello. In a newly installed terminal, WebRequest() returns 1009 and GetLastError() returns 5203 for one domain. Another terminal on the same VPS reaches the same domain without any problem. I tested with a simple GET script on a live chart, and the results are below.


Terminal A (build 6295, newly installed):
  my-server.example, 2 URLs     res=1009  err=5203  no body, no headers, 0-16 ms
  www.google.com, https/http    res=200

Terminal B (build 6230, same VPS):
  All of the above              res=200

Clean install of build 6296 (Windows Server 2019, another VPS, 10 other terminals running):
  my-server.example             res=200

On the failing VPS, Invoke-WebRequest in PowerShell returns 200 for the same domain. The domain has an IPv4 address only. The real domain name is replaced here, and I can share it by private message if needed.


I have three questions:

1. What does the return code 1009 mean? I could not find it in the documentation.

2. Is there a log or a setting that shows why the terminal fails for one host only?

3. Was anything changed in the WebRequest connection handling between builds 6230 and 6295?


Thank you for your help.