nginx redirecting all subdomains (when it shouldn't)

I have an nginx server running. I want it to redirect http://www.example.com to https://www.example.com, but not touch any other subdomains like http://foo.example.com.

For some reason, no matter what I add in the subdomain, it still gets rerouted. My webpage shows on www.example.com (as it should), but also on foo.example.com and example.com (as it shouldn't)

This is my example.com config file:

server {
  listen 80;
  server_name www.example.com;

  # For debug
  add_header X-debug-message "listen:80, server_name:www.example.com, redirect:https://$host$request_uri" always;

  # Riderect
  return 301 https://$host$request_uri;
}

server {
  listen 443 ssl;
  server_name www.example.com;

  # For debug
  add_header X-debug-message "listen:443, server_name:www.example.com, redirected:https://$host$request_uri" always;

  # SSL
  ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
  ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
  include /etc/letsencrypt/options-ssl-nginx.conf;
  ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
  root /var/www/example.com;

  # Redirect
  location / {
    proxy_pass http://192.168.1.224:80;
  }
}

Going to www.example.com shows me my webpage as expected. But going to foo.example.com also gives me my webpage - which it shouldn't. example.com also gives me the webpage.

Opening www.example.com in my browser, I see the following http header (as expected):

X-debug-message: DEBUG: listen:443, server_name:www.example.com, redirected:https://www.example.com/

Opening foo.example.com in my browser, I see the following http header (not as expected):

X-debug-message: DEBUG: listen:443, server_name:www.example.com, redirected:https://foo.example.com/

How can I make my nginx only redirect www.example.com ?

1. Ensure that the dns record for foo.yourdomain.com is actually created with dns provider

2. Create a second server block for the subdomain 'foo.example.com' otherwise all request to port 80 will be redirected to available server block, which in your case www.example.com - the server block should look like this:

        server {
           server_name foo.example.com;
           location / {
                root path/to/foo/index.html;
                index index.html index.htm;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_cache_bypass $http_upgrade;
                try_files $uri $uri/ /index.html;
           }
   
         listen 443 ssl; # managed by Certbot
         ssl_certificate 
         /etc/letsencrypt/live/example.com/fullchain.pem; # n 
           managed by Certbot
         ssl_certificate_key 
         /etc/letsencrypt/live/nextoma.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
       }
   

3. Add ssl certificate to the foo.example.com with the command:

   certbot --nginx -d foo.example.com
   

4. Restart nginx and recheck foo.example.com again