Nginx app entrence forbidden although DB and CMS synced and DR dir permissions set

On Ubuntu 16.04 with Bash I’ve established LEMP and I can’t access a WordPress app from browser although DB data is according (as I recall), and document root app dir has the right permissions (see below).

Nginx conf

• nginx.conf (all default).
• nginx default (all default).
• Nginx app conf.

WordPress app wp-config.php

This is the only part I changed in wp-config.php:

define('DB_NAME', 'example.com');
define('DB_USER', 'example.com');
define('DB_PASSWORD', 'example.password');

My resets before testing

chown -R www-data:www-data "$drt"/
chmod -R a-x,a=rX,u+w "$drt"/
systemctl restart nginx.service
/etc/init.d/php*-fpm restart

Current state

I get “entrance forbidden” when navigating to my domain in the browser.

No errors besides “entrance forbidden” appear in Nginx conf.

The DB user and the DB name are identical to one another and also identical to the app’s dir name

Desired state

Entrance permitted.

My question

Why is the entrance forbidden, given the above data? What I miss?

Notes:

1. This problem is unique to the WordPress app. It doesn’t happen with the non-HTTPS, PHPmyadmin app.