Howtoforge published a tutorial about installing Etherpad with Nginx and SSL on Debian 11.
How to Install Etherpad with Nginx and SSL on Debian 11
In this tutorial, you will install and configure the Etherpad Real-time Collaborative Editor on the Debian 11 Bullseye. This tutorial uses MariaDB as the database backend and Nginx web-server as a reverse proxy with the secure HTTPS enabled. In the end, you'll have the Etherpad installed and secured through secure HTTPS encryption.