Here’s a puzzle that trips up a lot of homelabbers: you want a publicly-trusted TLS certificate for a service that is only ever reachable on your LAN. No port forwarding, no exposing the box to the internet — but also no browser warnings, no self-signed-cert clicking-through, and no private CA to install on every device.

The specific thing that forced my hand: I wanted to connect Claude.ai’s remote MCP connector to my Home Assistant instance, and that connector flatly refuses plain HTTP. It demands a valid https:// endpoint. My HA is a sealed Green appliance at 192.168.1.18:8123, LAN-only, and I had no intention of exposing it to the world.

The answer is a nice combination of three ideas — a Let’s Encrypt DNS-01 challenge, a wildcard certificate, and split-horizon DNS — wired together with Traefik. This post is the worked example.