Install Jitsi on HestiaCP using docker

The official Jitsi Docker allows for easy installation on an empty VM without much difficulty. However, installing it on a VM managed by HestiaCP, which handles multiple (sub)domains, is not straightforward. After spending half a week trying and reading many frustrated accounts of failed attempts, I finally succeeded. Here is what I describe below. It is essentially the same as the official guide, but the key lies in properly defining the ports and the NGINX reverse proxy.