After several days of hard work with my Dlink DIR-655 router, opening ports I was on my way to give up. Eventually I opened DMZ (demilitarized zone) for the Apple TV, letting the Apple TV have no firewall at all. Still nothing worked.After 4-5 frustrating days, I found this thread.
Solution: I set my iPhone as a hotspot, connected the Apple TV to it and now it worked! My wife and I saw our first Netflix movie yesterday. She thinks I'm a genious... 🙂
I still don´t understand why my router settings don´t work. Is it something with my ISP? I don't know, but now it works. The steps I followed are from ike_e's list:
1. Disconnected the Apple TV from wireless network
2. Connected Apple TV to my iPhone hotspot
2. I set country/region on my Apple TV, this forces the Apple TV to download date/time and retrieve location info automatically
3. Once Apple TV running properly, I disconnected Apple TV from iPhone hotspot
4. Re-connected Apple TV to my wireless network
5. Works!
Thanks Ken and ike_e!