I can also use a differnt networkcard under SCP -> Network
e1000 = Intel Networkcard (the best for Windows 64 Bit)
rtl8139 = Realtek Networkcard (the best for Windows 32 Bit)
virtio = Networkcard form KVM (the best for Linux / or Windows with network driver)
Instructions are unfortunately only available in German on the Netcup wiki
Great tips! Work for me. It's in German, no wonder I was unable to find instructions about this in wiki