nginx не может отправлять заголовки HSTS, несмотря на то, что он настроен на это

Я настраиваю для себя сайт с помощью nginx и letsencrypt, и я хотел настроить предварительную загрузку HSTS для дополнительных преимуществ безопасности, однако, когда я проверяю URL-адрес с помощью нескольких разных сканеров, заголовки HSTS не отправляются.

Вот соответствующий блок в конфигурации сервера:

 server {

    root /var/www/html/pyroballpcbs;
    index index.php index.html index.htm;

    server_name pyroballpcbs.com www.pyroballpcbs.com;
    server_tokens off;

    client_max_body_size 20M;

    location / {
        #try_files $uri $uri/ =404;
        try_files $uri $uri/ /index.php$is_args$args;
    }

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
    }

    location = /favicon.ico { log_not_found off; access_log off; }
    location = /robots.txt { log_not_found off; access_log off; allow all; }
    location ~ /\.ht {
        deny all;
    }
    location ~* \.(css|gif|ico|jpeg|jpg|js|png)$ {
        expires max;
        log_not_found off;
    }

    #listen [::]:443 ssl ipv6only=on default deferred; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    #Config to enable HSTS
    add_header Strict-Transort-Security: "max-age=63072000; includeSubdomains; preload" always;
    ssl_certificate /etc/letsencrypt/live/pyroballpcbs.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/pyroballpcbs.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
    #Disable insecure TLSv1.0
    ssl_protocols TLSv1.2 TLSv1.3;

}

server {
    if ($host = www.pyroballpcbs.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = pyroballpcbs.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    listen 80;
    #listen [::]:80;
    add_header Strict-Transort-Security "max-age=63072000; includeSubdomains" always;

    server_name 10.1.10.15 pyroballpcbs.com www.pyroballpcbs.com;
    return 301 https://$host$request_uri; # managed by Certbot
}

Вот результат работы сценария nmap, предназначенного для проверки заголовков безопасности:

$ nmap -p 443 --script http-security-headers pyroballpcbs.com

Starting Nmap 7.01 ( https://nmap.org ) at 2019-03-13 00:39 PDT
Nmap scan report for pyroballpcbs.com
Host is up (0.00031s latency).
PORT    STATE SERVICE
443/tcp open  https
| http-security-headers:
|   Strict_Transport_Security:
|_    HSTS not configured in HTTPS Server

hstspreload.org также показывает ту же проблему, как и сканер ssllabs.com:

https://hstspreload.org/?domain=pyroballpcbs.com

https://www.ssllabs.com/ssltest/analyze.html?d=pyroballpcbs.com&s=73.241.63.225

и вывод статуса службы nginx:

$ sudo service nginx status
â nginx.service - nginx - high performance web server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2019-03-13 00:39:48 PDT; 12min ago
     Docs: http://nginx.org/en/docs/
  Process: 19114 ExecStop=/bin/kill -s TERM $MAINPID (code=exited, status=0/SUCCESS)
  Process: 19116 ExecStart=/usr/sbin/nginx -c /etc/nginx/nginx.conf (code=exited, status=0/SUCCESS)
 Main PID: 19118 (nginx)
    Tasks: 2 (limit: 4915)
   CGroup: /system.slice/nginx.service
           ââ19118 nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
           ââ19119 nginx: worker process

Mar 13 00:39:48 mail.pyroballpcbs.com systemd[1]: Stopped nginx - high performance web server.
Mar 13 00:39:48 mail.pyroballpcbs.com systemd[1]: Starting nginx - high performance web server...
Mar 13 00:39:48 mail.pyroballpcbs.com systemd[1]: nginx.service: PID file /var/run/nginx.pid not readable (yet?) after start: No such file or directory
Mar 13 00:39:48 mail.pyroballpcbs.com systemd[1]: Started nginx - high performance web server.