By default php-fpm listen on tcp port 9000.
It is better to use socket instead of tcp as it is less overhead.
To change, edit file
vi /etc/php/7.0/fpm/pool.d/www.conf
Find
listen = 127.0.0.1:9000
Replace with
listen = /var/run/php-fpm.sock
Now edit nginx config.
vi /etc/nginx/sites-enabled/yoursite.conf
Find
fastcgi_pass 127.0.0.1:9000;
replace with
fastcgi_pass unix:/var/run/php-fpm.sock;
Now restart nginx and php-fpm
service nginx restart service php7.0-fpm restart
