Problem configuring tusd over https on Nginx

I am trying to setup tusd with Uppy on https without success. It works well on http.

Here's my nginx conf file:

server {
  listen 80;
  listen[::]: 80;
  server_name
  DOMAIN.com
  www.DOMAIN.com;

  root / srv / users / DOMAIN / apps / DOMAIN / public;

  access_log / srv / users / DOMAIN / log / DOMAIN / DOMAIN_nginx.access.log main;
  error_log / srv / users / DOMAIN / log / DOMAIN / DOMAIN_nginx.error.log;

  proxy_set_header Host $host;
  proxy_set_header X - Real - IP $remote_addr;
  proxy_set_header X - Forwarded - For $proxy_add_x_forwarded_for;

  include / etc / nginx - sp / vhosts.d / DOMAIN.d
  /*.nonssl_conf;
      include /etc/nginx-sp/vhosts.d/DOMAIN.d/*.conf;
  }

  server {
      listen       443 ssl http2;
      listen       [::]:443 ssl http2;
      server_name
          DOMAIN.com
          www.DOMAIN.com
        ;

      ssl_certificate_key      ssl/DOMAIN.key;
      ssl_certificate          ssl/DOMAIN.combined_crt;

      root   /srv/users/DOMAIN/apps/DOMAIN/public;

      access_log  /srv/users/DOMAIN/log/DOMAIN/DOMAIN_nginx.access_ssl.log  main;
      error_log  /srv/users/DOMAIN/log/DOMAIN/DOMAIN_nginx.error_ssl.log;

      proxy_set_header    Host              $host;
      proxy_set_header    X-Real-IP         $remote_addr;
      proxy_set_header    X-Forwarded-For   $proxy_add_x_forwarded_for;
      proxy_set_header    X-Forwarded-SSL   on;
      proxy_set_header    X-Forwarded-Proto $scheme;

      include /etc/nginx-sp/vhosts.d/DOMAIN.d/*.ssl_conf;
      include /etc/nginx-sp/vhosts.d/DOMAIN.d/*.conf;


  location /files/ {
        #resolver 8.8.8.8 4.2.2.2;

        proxy_pass  http://localhost:3020/files;   
        proxy_set_header Host $host; 
        proxy_set_header X-Real-IP $remote_addr;    

        # Disable request and response buffering    
        proxy_request_buffering  off;               
        proxy_buffering          off;                
        proxy_http_version       1.1;                 

        # Add X-Forwarded-* headers so that response can reference https and
        # originating host:port                                                     
        proxy_set_header X-Forwarded-Host $hostname;                       
        proxy_set_header X-Forwarded-Proto $scheme;                                
        proxy_set_header X-Forwarded-Proto https;      
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;            

        # Allow proxying of websockets if required               
        proxy_set_header         Upgrade $http_upgrade;         
        proxy_set_header         Connection "upgrade";        
        client_max_body_size     0;  
    }
  }

At another conf file I have this additional configuration:

location / {
    proxy_pass      $backend_protocol://$backend_host:$backend_port;
}

At Chrome console I have the following output:

upload.js:2 OPTIONS https://DOMAIN/files/2b775a112504ed1222c6ffdd4fbdac03+Dc99JI0Zvgh54FXVfpp5K32GAiZBjV5bY-d9tzj8fDL1FxNKKZrHP_SBE6OERG8SWAm1ZjqtjYMVWSvWCQLba0qsR8krfVBYw8ApHqIBO7DG9Bn1t_tv_a6nuuTuqlXC net::ERR_NAME_NOT_RESOLVED

Notice the domain without the .com extension!

I tried all combinations of configuration, commenting the configuration lines without success. Can you spot the mistake?

A contractor solved it for me and the solution is neat. He did it instead configuring Apache.

At the first nginx conf file he removed the "location /files/" section entirely. At the apache conf file, he added the following lines:

    ProxyPass /files http://localhost:3020/files
    ProxyPassReverse /files http://localhost:3020/files

And it worked.