Apple TV 2 (ATV2) says: “Activation: Failed“

Im using an Apple TV 2 and everything is weird. I have jailbreaked it in the past, but regretted it. Ive restored it through iTunes. First, I couldnt log into anything. iCloud, iTunes, etc. It worked when I used my iPhone „as a router“ and connected the atv to it. I thought it would be the date and time, but I was wrong. All it did when I connected my iPhone with it, was that it had Internet connection and I could finally log in into iCloud. If i disconnected, and connected with my wifi again (Fritz!BOX7490), everything was the same. The solution was to connect it vie ethernet.

It still says “Activation: Failed“ in the About section. Can anyone help?

Thanks in advance.