403 Forbidden how to fix?

Question

Nginx

There are two sites on regru hosting, everything was fine, but today at lunch they suddenly began to give an error "403 Forbidden Access to the page is denied". This error is displayed on the main page and on the /wp-admin login page. The rest of the pages work fine.
Restoring a backup when the site was 100% working fine, disabling plugins, replacing the .htaccess file, checking directory and file permissions, checking index pages - nothing helped. I wrote to the hoster - they answered that they did not find any problems on their part, they recommended making a backup copy. Actually, now there is no idea at all how to fix the error.

Answer 1

hosted by regru

It's time to get out of this horror.

Answer 2

logs