@Alexander_C This is a late reply to your question, but I’ve found that Plesk will block some Strapi requests. I have had to go into the Plesk Web Application Firewall and disable rules 211760 and 210492.
Also, for anyone now using Strapi v5 the server.js file has changed (different syntax on second line):
import strapi from '@strapi/strapi';
const app = strapi.createStrapi({ distDir: './dist' });
app.start();