Wrong domain appearing for SSL

Hi there, I’m very new to all this, so excuse me if this is obvious but I’ve done a lot of Googling and seem to see no one else with this issue.

Last night I was able to set up SSL on a Hass.io build on a RasPi 4 using Let’s Encrypt (but not DuckDNS but a Google Domain with a custom DDNS updating script). It works perfectly well and now https://MY-DOMAIN.com loads up just fine both off and on my network. I did all this so that I could utilize the Google Assistant and SmartThings integrations (I have a lot of hardware for both). However, as soon as I go to set up SmartThings, it tells me that the callback hook that SmartThings is going to use is https://MY-LOCAL-IP/api/webhook/TOKEN-PATH. The problem is that SmartThings obviously can’t connect using my local IP and obviously my SSL cert is not for my local IP but for MY-DOMAIN, but there’s no place to change what domain it’s trying to target. When I set up the mobile app, I actually had the same experience but the mobile app allows you to just type in a URL directly and that worked fine. I’d figure that I should just go into the config and change http.server_host but obviously as the docs say, you can only change that property if you’re running HomeAssistant Core, not a full Hass.io build. And confirmed! Totally breaks my instance to put anything in that property and I have to go into the machine and manually fix the config from vi and then restart.

tl;dr How do I make the application respect the domain that I’m running on?

I also posted this question on Reddit and u/jmpavlec hit it on the head.

"Did you set the ‘external_url’ in your configuration.yaml?

(It was linked via the SmartThings docs). I have no experience with it so just going by what I read there…"

That was indeed the issue.