Network devices are somewhat special, since besides being able to add them the standard way, there's a much easier one to configure them through the -net nic parameter.

Also, please note that -device doesn't suppress the default configuration, so it might not do what you intend.

Adding a card

Simply specifying -net nic on the command line adds an interface. You can select the hardware being emulated using the model modifier.

Example:

qemu -net nic,model=ne2k_pci ...

Network card models

For PC emulation

qemu-system-<arch> -net nic,model=<model>

In this command, <arch> and <model> should be replaced with the appropriate architecture and model you intend to use.

Others emulated architectures

You have to launch this command to list emulated network card