Jitsi-meet server ubuntu 18.04 LTS install in virtualbox

Hello. I am a student who is building jitsi-server with ubuntu 18.04 in virtualbox.
While referring to the jitsi-meet handbook self-hosting guide, etc., a question arises during the installation process.

  1. Designate the server’s domain name for external access.
    Here, next to, add the DDNS name set in the router. I wonder whether .iptime.org is included in the DDNS name.
    Also, in the case of me, since I am using it as a virtualbox, there is also a virtualbox virtual ip, and I am curious what DDNS name should be used next to it.
    Also, in the case of hostname, I am wondering if it is okay to do anything or if I can subtract .iptime.org from the DDNS name.

And I don’t know if it’s right, so I went ahead and installed it.

However, when I ran install-letsencrypt-cert.sh to make it mobile, the following two errors occurred.
-Domain / type connection -> Timeout during connect (likely firewall problem)
-An unexpected error occured: There were too many requests of a given type :: Error creating new order :: too many failed authorizations recently: see https://letsencrypt.org/docs/rate-limits/
Is there a solution?

And if you run https://DDNS hostname <- DDNS hostname of the router to connect to chrome and have a video conference, it says that it cannot connect to the site. I think it’s the same problem as the previous picture, but it’s a virtualbox, so I think it could be…!!

The Let’Encrypt client used by default Jitsi setup is not modified in this context, it’s the out-of-the-box certbot from Ubuntu install, and as such problem you encounter when using it are not specific to Jitsi. You would be better inspired to go to the Let’s Encrypt forum where your problem - most likely a network related problem (firewall or natting error) - could get better help.