url-retrieve fails on most HTTPS sites

[Nicolas Graner <nicolas@graner.name>]

Hello all,

using 26.1 on Debian, I try to open various web pages with url-retrieve.
It works with all HTTP and some HTTPS connections, but fails with most
HTTPS. For instance with Wikipedia:

  (switch-to-buffer (url-retrieve "https://wikipedia.org/" '(lambda (&rest ignore))))

The buffer that shows up is empty. Tracing url-http-async-sentinel gives:

======================================================================
1 -> (url-http-async-sentinel #<process wikipedia.org> "open
")
1 <- url-http-async-sentinel: nil
======================================================================
1 -> (url-http-async-sentinel #<process wikipedia.org> "connection broken by remote peer
")
1 <- url-http-async-sentinel: nil

In contrast, The Conversation is OK:
  (switch-to-buffer (url-retrieve "https://theconversation.com/fr/" '(lambda (&rest ignore))))
works fine, the buffer contains HTTP headers followed by à HTML page.

I don't use a proxy. The result is the same whether url-privacy-level
is 'none or 'paranoid.

Any suggestions as to what could make some sites close the connection,
or how I could find out more?

Thanx for your help.
Nicolas