DuckDNS when Internet is down

What is the proper method on connecting to a device via a local connection that has DuckDNS set up ? I can’t seem to find a straight answer. Mainly this would be for the app on android device but even on a laptop I can’t connect to the IP:port. I even tried adding the internal IP:port to Configuration>General Configuration>Internal URL. Still no go. If my internet is down, all my automations still work. I just can’t turn on/off any lights because of DNS resolution. I have Asus RT-86 if I need to configure something there. I am not a networking guy.

Does it not connect at all or do you just get the security warning?

Are you using or (replacing with your applicable IP) Do both render the same result?

I was getting empty response using both http and https. So I updated the OS, supervisor and core as I was behind a couple versions. Now the https does work so that is good. Regarding the mobile app, what needs to be done to allow that to connect internally? I can open web browser and connection using the internal IP, but setting the app with internal will fail as the cert is only looking for that duckDNS domain I suspect. I am working on setting up a couple tablets around my place and they use the mobile app.

In the app config are settings for the internal and external URL.

setting internal URL with local IP fails. I think you can force the cert issue but requires a rooted device?? Not too sure.

I struggled with this a year or more ago. I ended up adding NGINX from the supervisor add-on store. It simplified things so local connections are HTTP and external connections are HTTPS.

A couple of weeks back my ISP was down for few hours and presented the opportunity to test out HA with no internet. My computer with ethernet connection to router was fine, my iPad wifi only model worked as well. My phone on the other hand was not able to to connect to the router complaining that there was no internet. And then the internet came back up…

hmm interesting I will have to check that out. It is a rare occasion that the internet would be down however it can happen. The fact that doing hass updates now allows me to access via https local IP, although with security warning, at least lets me turn on or off a light where as before I had no option other than physically pull the power. Mainly have bulbs in my automation.

Easiest way would be, if app will allow to accept invalid cert, or add it to exemptions