VPN recognition abroad

[BKK20 0]

At home I use AirVPN on my router constantly and I never had any problem while watching Netflix on other devices in my network.

When I am abroad, first I connect to my own HomeVPN (self configured). My own VPN Server is running and connected with my router again. This means, after my connection to my own VPN Server I am surfing over my AirVPN connection via my router again

Why and how does Netflix recognize that I am abroad?
 

[OpenSourcerer 1435]

Did you check your browser? Obvious things like geolocation and WebRTC, but also time zone and language settings?

That said, Netflix do know you're using a VPN. They're quite effective in shutting down access to them. Maybe it's simply that.

[BKK20 0]

I just opened netflix app without any browser

[Stalinium 44]

An installed app has infinitely many more options to acquire your geolocation data. (You are being punished by DRM, so why would you keep paying them?)
It is much easier to lock down a browser to not leak info. If you want to get down to it, start with a computer browser. Make sure the obvious things are taken care of first: language settings, regional, time zone, WebRTC, DNS leaks and geoDNS (you're sent a server IP that's nearby). Use browserleaks website to verify.
If it works, try to repeat on mobile browser.
I wouldn't be surprised if the system's DRM libraries (like Widevine) have or soon will have user's geolocation detection. When that happens, it'll be game over for watching abroad. They obviously care about user experience