ELB, Nginx and redirecting http to https - 408 requests timeout

Question

I have this configuration:

• The Amazon Elastic Load Balancer (ELB) routes port 80 to port 81 and port 443 to port 80
  • The cert is handled in ELB
• Nginx listens to port 80 and 81
  • Port 81 redirects to https
  • Port 80 is the main server

The nginx server block for port 81:

server {
    listen 81 default_server;
    listen [::]:81 default_server;
    server_name _;
    return 301 https://$host$request_uri;
}

The problem is that http requests timeout (408). Suggestions?