Android jitsi meet does not work with dockerized jitsi backends

Hello!
I’m the new guy to build up Jitsi and try it.
I started Jitsi backend commponent from this guide https://github.com/jitsi/docker-jitsi-meet
It’s ok with LAN web access, but android app does not work.
My cert is self signed.
By the way : if i want to obtain Cert using letsencrypt, so i have to put system in a live DNS enabled server ?
Many thanks!