I cannot get a certification

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I tried using sudo certbot -a webroot -i nginx -w /var/www/html -d harryisback.org. It still gave me a dns error.

# HTTP Server Block
server {
    listen 80;
    server_name harryisback.org immich.harryisback.org;

    # Redirect HTTP to HTTPS
    return 301 https://$host$request_uri;
}

# HTTPS Server Block
server {
    listen 443 ssl;
    server_name harryisback.org immich.harryisback.org;

    ssl_certificate /etc/ssl/certs/ssl-cert-snakeoil.pem;
    ssl_certificate_key /etc/ssl/private/ssl-cert-snakeoil.key;

    # Allow large file uploads
    client_max_body_size 50000M;

    # Set headers
    proxy_set_header Host              $http_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-Proto $scheme;

    # Enable websockets
    proxy_http_version 1.1;  # Use HTTP/1.1 for WebSocket
    proxy_set_header Upgrade $http_upgrade;  # Handle WebSocket upgrade
    proxy_set_header Connection "upgrade";  # Handle WebSocket upgrade
    proxy_redirect off;

    # Set timeouts
    proxy_read_timeout 600s;
    proxy_send_timeout 600s;
    send_timeout 600s;

    # Main location block
    location / {
        proxy_pass http://192.168.1.55:2283;  # Backend server
    }
}

this is how my conf file look now.