CAmkES PicoServer on QEMU x86_64 connectivity

Hello seL4 experts,
in order to evaluate seL4 + CAmkES for our needs I am trying to build a custom example project with a PicoServer and emulate it via QEMU x86_64.
A listener component should simply accept the incoming data from the PicoServer and print it out.
The build itself works and also starting the emulation works with the following command:

./simulate --machine=“q35” --extra-qemu-args=“-device intel-iommu,intremap=on -netdev user,id=mynet0,net=,hostfwd=tcp::5555-:4321 -device e1000,netdev=mynet0 -object filter-dump,id=fd0,netdev=mynet0,file=dump.dat”

I see some output that various Protocols (Ethernet → TCP) are registered, so I assume the initialization works (to some extend).

The PicoServer is configured to have IP address (which qemu assigns).
Now on the host I can run a netcat localhost 5555, which should forward to the qemu machine.
But nothing happens.

In the dump.dat I can see that the qemu gateway sends an ARP request asking “Who has” but does not get an answer.

Most likely I misconfigured something on the NIC either in qemu or the CAmkES component (ethdriver).

Can anyone share some experience here?
Can anyone tell me how to activate the debug messages in the ethdriver?