Hi, > > Does someone have an idea what I did forget to check/verify? > You can try to enable debugging: sysctl hw.usb.axge.debug=255 Or: Try to log the USB traffic using "usbdump" usbdump -i usbusX -f y -s 65536 And look for errors like "ERR". Did you verify two such adapters back2back with iperf, for packetloss and other issues? --HPS