Certbot

Nginx

sudo apt install certbot python3-certbot-nginx

sudo certbot --nginx

Manual

sudo certbot certonly --manual \
    -d *.example.com -d example.com \
    --agree-tos \
    --manual-public-ip-logging-ok \
    --preferred-challenges dns-01 \
    --server https://acme-v02.api.letsencrypt.org/directory \
    --register-unsafely-without-email \
    --rsa-key-size 4096

Nginx config

server {
    listen 80;
    listen [::]:80;
    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    server_name example.com *.example.com;
    root /var/www/example.com/public;
    index index.html index.php;
    
    ssl_certificate /etc/letsencrypt/live/example.com/chain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
    ssl_protocols TLSv1.1 TLSv1.2 TLSv1.3;
    ssl_ciphers EECDH+CHACHA20:EECDH+CHACHA20-draft:EECDH+AES128:RSA+AES128:EECDH+AES256:RSA+AES256:EECDH+3DES:RSA+3DES:!MD5;
    ssl_prefer_server_ciphers on;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;
    
    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }
    
    location ~ \.php$ {
        try_files $fastcgi_script_name =404;
        fastcgi_index index.php;
        fastcgi_pass unix:/var/run/php/php8.2-fpm.sock;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    }

    location ~ /\.ht {
        deny all;
    }
}

Plex

sudo openssl pkcs12 -export \
    -out /var/lib/plexmediaserver/certificate.p12 \
    -in /etc/letsencrypt/live/plex.example.com/cert.pem \
    -inkey /etc/letsencrypt/live/plex.example.com/privkey.pem \
    -certfile /etc/letsencrypt/live/plex.example.com/chain.pem \
    -passout pass:PASSWORD \
    -certpbe AES-256-CBC -keypbe AES-256-CBC -macalg SHA256

sudo chown plex:plex /var/lib/plexmediaserver/certificate.p12