Hi,
Apologies for not replying in German as I dont understand this language. I have translated it in English with the help of google and replying back to you.
If I understood correctly, your problem statement is - You are not able to find NIC drivers with new machine arrived and you are using GSS 2.5.
What Pre-os are you using? for Winpe you need to add the NIC driver thorugh Ghost boot wizard, select Pre-os Winpe and click edit option, select winpe and add the appropriate network drivers. Create boot package on your USB stick.
Other option is to create boot package using pc-dos pre-os.
Regards,
Nitin