Externe Festplatte wird nicht mehr erkannt

Check this link for a possible solution:
https://support.xbox.com/en-US/games/troubleshooting/console-doesnt-detect-external-storage

Hello

Go here

support.xbox.com/.../cant-connect-to-xbox-live-solution

Wenn Sie einen WLAN-Adapter auf der Xbox zu verwenden, führen Sie dann eine Network Connection Test durch:

• Drücken Sie Ihre Guide-Taste
• Navigieren Sie zu Einstellungen
• Wählen Sie System Settings
• Wählen Sie Netzwerkeinstellungen
• Wählen Sie das Netzwerk, die Sie verwenden
  
• Wenn Sie dazu aufgefordert Ihr Passwort eingeben
  
• Test Xbox Live Connection

Bitte beachten Sie: Wenn Sie aufgefordert werden, einen WLAN-Adapter anschließen, dann dein ist in need of repair.

Hoffe, das Ihnen helfen kann. Bitte lassen Sie uns wissen, wenn es funktioniert.

Translation to English:

If you use a wireless adapter on your Xbox, then run a Network Connection Test by:

• Pressing your Guide button
• Navigate to Settings
• Select System Settings
• Select Network Settings
• Select the Network you will use
• If prompted enter your password
• Test Xbox Live Connection

Please note: If you are prompted to connect a wireless adapter, then yours is in need of repair. Please let us know if this helps you.

I used this, but it didn´t help. I hope i can describe it in english^^ Before a few weeks a lightning stroke in our house. My router, a Speedport W 723 V type A from the German Telekom, was destroyed. After a few days the new router was there. I used the
lan cable to connect router and xbox, but it always tells me, that there is no lan cable to edit the connection settings, so i cant do step 3 of the cable network. I used different cables and different ports, i used the lan cable of my pc too and it didnt
work. Can it be, that the thunder destroyes the lan port of my xbox so i can´t go online? Can i use a wireless stick to go online or is it not working? My Xbox is the elite with a 120 gb HDD, xbox is without gurantee, it´s to old. Hope someone can help me
by this problem and sorry for my englisch^^

I would actually expect that it was destroyed as well if it was online or on at the time, but if it turns on at all it disagrees with that, when a comp has this happen, its fried temporary and you have to replace parts to use it at all. So if the xbox fried
the same way it shouldn't be usable at all. It is possible that it just messed up part of the xbox, but i would look for other solutions really. there's an incredibly large amount of possibles for connection problems. Such as;

firewalls, wired vs wireless, reseting router / modem, bad Ethernet cords, the list goes on, rule out connection problem before messing with xbox's hardware. mein dutche schlecht