Nginx keeps bad redirect for firefox - firefox

Question

i am trying to solve problem. I want to redirect all urls starting with www to non-www version of site. In chrome and opera, it works well.
But when i go to firefox and open http://www.example.com it starts downloading page (mime-type octet/stream), on https://www the connection is not reliable. In other browsers it set mime-type text/html.
server {
listen 80;
listen [::]:80;
server_name www.example.com;
return 301 https://example.com$request_uri;
}
server {
listen 80;
listen [::]:80;
root /var/www/domain/www;
index index.php;
server_name example.com;
return 301 https://$server_name$request_uri;
}
server {
root /var/www/domain/www;
# Add index.php to the list if you are using PHP
index index.php;
server_name example.com;
location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
try_files $uri $uri/ /index.php?$args ;
}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
location ~ \.php$ {
include snippets/fastcgi-php.conf;
fastcgi_pass unix:/var/run/php/php7.1-fpm.sock;
}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
location ~ /\.ht {
deny all;
}
listen 443 ssl; # managed by Certbot
ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/example.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
}