http://arcani5qce7mhpqnemrmj2mv5dx2qjxnfzw5d3vzuvs5bqlzb65nkbyd.onion/guides/prosody.php
If you want to setup something to host federated chatrooms (MUCs), a file upload service, and video/voice calling--then it'll take much longer. You can add/remove services at any later time. As a preview, the simplest example of a server setup on Ubuntu in under 8 commands for just enough configuration to start interacting on other servers would be (as executed as root): add-apt-repository -U https://packages.prosody.im/debian -c main
apt update
apt install prosody certbot
certbot -d...