Trying to redirect non-www to www (Certbot, Nginx), but the opposite occurs. What's causing this?

I want to redirect all domain traffic to https://www.mysite.com.

Instead, everything is going to https://mysite.com.

I’m not sure what I’m doing wrong. Any help would be greatly appreciated!

server {

  root /var/www/mysite.com;
  index index.html index.php index.htm index.nginx-debian.html;

  server_name mysite.com www.mysite.com;

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

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

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

  location ~ /\.ht {
    deny all;
  }



  listen [::]:443 ssl; # managed by Certbot
  listen 443 ssl; # managed by Certbot
  ssl_certificate /etc/letsencrypt/live/mysite.com/fullchain.pem; # managed by Certbot
  ssl_certificate_key /etc/letsencrypt/live/mysite.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

}

server {

  return 301 https:///www.mysite.com$request_uri;

  listen 80;
  listen [::]:80;

  server_name mysite.com www.mysite.com;
  return 404; # managed by Certbot

}