The UPNP IGD integration has a UPNP IGD External IP entity where the public IP of my router is displayed, but displaying it is the only thing I can do with it.
I’d like to have a trigger for it so that I can execute an automation when the value changes. I want to use it to send me a notification to my phone. That way I know that I have to update the DNS entry for my domain or even automate it with home assistant without needing a dynamic DNS service.
The following will trigger on any state change.
trigger:
- platform: state
entity_id: snsor.public_ip
FYI I use the following sensor instead of UPNP as it tends to fail for some reason at random times.
- platform: dnsip
name: Public IP
If there is a way to execute a trigger for any state change if would be nice having it in the frontend too, at least for the newbies like me that just started trying to automate things with Home Assistant and don’t control the YAML editing yet 
Do I need to install some kind of integration or something first for that one to work or does it work as is?
