Can some one explain to me how the homey APP knows what my home IP address is?
If the Homey app connects directly via port forwarding to my Homey it needs to know my homey IP, if it does not use the Homey Cloud how does the APP know which is my home IP address?
If the app does not know it, you will have to provide the ip-address. But the app may already know and remember, as the first time you use the app it is on your local network and it can find out by https://whatismyipaddress.com/
You IP address is also known by the Athom server, the app might get it from there.
So there are plenty ways how it can be done.
Also, when you enable port forwarding, homey tests if it is reachable via port forwarding, so it has detected your public IP-address. And Homey can transfer the ip-address to the app.
It is getting more complicated when you have more Homeys and more users. So the best way to find out is to ask Athom for the design 
It still does, both for authentication and to find out what your external IP address is.
Hello, are there any plans to introduce the fowarding port on Homey Pro 2019 boxes?
Does it matter if you use the ethernet ip address or the wireless ip address?
That would explain it, but then then text is not clear, it suggest you connect 100% directly but it does not.
When the cloud is down (for what reason ever) then you still cannot connect, it cannot find your Homey and it cannot authenticate.
No you need to forward the port the IP which you Homey is using in your local network, it doesnāt matter how homey is connected (wired or wireless).
It seems like Homey wants to accommodate its users. But of course they canāt just change their entire system architecture and concept in a jiffy.
This is just a half-baked implementation that sounds nice in marketing material but comes with a bunch of caveats that make it a bit pointless.
