This video and the accompanying article explain how to set up easy SSL certificates in a HomeLab environment using DNS-01 validation.  This method should also work for other types of locally-hosted services (in other words, servers on your local network that have a web interface, but that aren’t exposed to the Internet).  The problem is that obtaining SSL certificates for internal HomeLab services can be challenging, especially when you don’t have a public IP or don’t want to expose your services to the internet.  The video and article demonstrate how to use DNS-01 validation to obtain SSL certificates from Let’s Encrypt using your internal DNS server. This approach eliminates the need for a public IP or exposing services to the internet.

Article: Easy, quick and free valid SSL certificates for your homelab using DuckDNS and ACME DNS-01 (Wolfgang’s Blog)