Redirect from HTTP to HTTPS does not work

[StSch]

This is my configuration:

server {
  listen 80;
  server_name shell.*;
  return 301 https://$server_name$request_uri;
}

server {
  listen 443 ssl;
  server_name shell.*;
  
  location / {
    proxy_pass http://192.168.0.16:4200;
  }
}

I am using a Dynamic DNS Service to access NGINX running on my Raspberry
Pi.

The configuration perfectly works for https://shell.raspi.dyndns.com but not
for http://shell.raspi.dyndns.com (message: The requested URL could not be
retrieved. The system returned: Operation timed out.).

Any idea what the problem could be and how to fix it?

Regards,
Steffen

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,260913,260913#msg-260913