500 error on index.php with nginx + php-fpm

Before starting, I'd like to ssay this is my first experience with VPS, I have an Ubuntu 18.04 64bit minimal server. > For everything I tried so far I didn't tried using complex application. Just plain html file with Hello message and WordPress blank installation. To begin with, I'm installing Vesta Panel because it's easier for me to control some basic tasks and configurations. In order to install this panel, I'm using nginx + php-ftpm. After I install WordPress with this configuration I'm getting 500 error with this message: 2020/06/23 23:09:09 [error] 12335#12335: *11 connect() failed (111: Connection refused) while connecting to upstream, client: x.x.x.x, server: example.com, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9001", host: "example.com" This error only appears when I try to access the WordPress index page, or any file with the naem index.php, if it's an index.html file it loads properly. --- After that I restored the VPS and installed Vesta Panel using nginx + apache. With this configuration, WordPress is working as expected. When I access my domain example.com the steps to create an WordPress website appears as expected. With both configurations, the folder holding all the websites files is /home/admin/web/{domain.com}/public_html. --- Edit: As requested in the comments, I'm adding more information to the question. systemctl status php-fpm.service returns: php-fpm.service - LSB: starts php7.2-fpm Loaded: loaded (/etc/init.d/php-fpm; generated) Active: active (exited) since Wed 2020-06-24 01:44:40 UTC; 10h ago Docs: man:systemd-sysv-generator(8) Tasks: 0 (limit: 614) CGroup: /system.slice/php-fpm.service Jun 24 01:44:40 agdevision.com.br systemd: Starting LSB: starts php7.2-fpm... Jun 24 01:44:40 agdevision.com.br systemd: Started LSB: starts php7.2-fpm. sudo journalctl -u php-fpm.service returns: -- Logs begin at Fri 2019-03-08 08:44:31 UTC, end at Wed 2020-06-24 12:08:35 UTC. -- Jun 24 01:44:40 agdevision.com.br systemd: Starting LSB: starts php7.2-fpm... Jun 24 01:44:40 agdevision.com.br systemd: Started LSB: starts php7.2-fpm.