OPTIONS https://api.example.com/endpoint net::ERR_CONNECTION_TIMED_OUT

OPTIONS https://api.example.com/endpoint [250ms]
null

location /{
     proxy_pass http://127.0.0.1:5000;

     add_header 'Access-Control-Allow-Header' 'Origin, Content-Type, Accept, Authorization';
     add_header 'Access-Control-Allow-Methods' 'POST, GET, OPTIONS';
     add_header 'Access-Control-Allow-Origin' 'http://example.com';
     if ($request_method = 'OPTIONS') {
         add_header 'Access-Control-Allow-Origin' 'http://www.webapp.com';
         add_header 'Access-Control-Allow-Methods' 'POST, GET, OPTIONS';
         add_header 'Access-Control-Max-Age' '1728000';
         add_header 'Content-Type' 'text/plain; charset=UTF-8';
         return 200;
     }