Hi thanks for the reply
setting of eth0 is: 1000 Mbps, full duplex, mtu 1500
I tried connecting my laptop directly to the server (using a different/new cable): no change
I tried booting a live-Linux on my PC to rule out windows/driver issues: no change
I tried a Linux VM directly on the server, connected to br0: here is everything ok.
So it seems that something is wrong with the NIC. Hardware oder setting.
I will try to boot the server with a live-Linux to test once I have time for that.
It cloud be a coincidence but it is suspicions that the download is limited to 500 MBit/s, so half of GBit. Is there maybe some QoS etc. in the system I am not aware of?
Edit: Tried booting a live-Linux on my server an did an iperf to my PC. Up- and Download are fine. So it must be a setting in unraid.