example.nginx.conf

server {
    listen       80;
    server_name SITE.dtdemo.ru;

    set $site "216-aem12";

    access_log  /var/log/nginx/sites/$host.access.log main;
    root   /var/www/$site;

    include telescope;
}

server {
    listen       80;
    server_name  OTHERDOMAIN.ru SITE.downstream.ru;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name  OTHERDOMAIN.ru SITE.downstream.ru;

    set $site "SITE";
    # Use the Let’s Encrypt certificates
    ssl_certificate /etc/letsencrypt/live/SITE/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/SITE/privkey.pem;
    # Include the SSL configuration from cipherli.st
    include ssl-params.conf;

    access_log  /var/log/nginx/sites/$host.access.log main;
    root   /var/www/$site/current;

    include telescope;
    pagespeed LoadFromFile "https://SITE.downstream.ru" $document_root;
}

Let's encrypt get cerfificate

# service nginx stop && certbot certonly --standalone -d ar2015.rosatom.ru -d rosatom15.downstream.ru && service nginx start