Looking at my browser developer log after one of these ‘disconnected’ incidents, I can see that the browser is trying to connect to the name that was given during the Jitsi installation procedure. What this means is that the name you put in that box during installation must be the permanent domain name of your server. This is very important, as that name gets sprinkled all through the various configuration files and there is no way to change it later.
So it has to be either a static IP address or a domain name that you control. It could be a name you registered at one of the Dynamic DNS service, or it could be a name chosen for this purpose and registered at Namecheap or one of the other DNS registration services. Or both: make the registered name have a CNAME record pointing to your Dynamic DNS name, as this will allow you to point it somewhere else in the future without changing the name your clients know.
I currently have a jitsi meet installation running on AWS but it gets this disconnect error because the domain name I configured it for, and registered, has not yet propagated to all the world’s DNS servers, a process that can take 48 hours. AND you can not do the final installation step of replacing the self-signed certificate with a letsencrypt one until that domain name is working.
I verified that this is the case by faking out my local desktop machine by putting an entry in /etc/hosts that points directly to my AWS instance.