If the vm initiatively initiates the iperf, the connection will be directly disconnected. Otherwise, it will not, but the speed is very slow 0k/s.

My laptop:

D:\Users\th>iperf3 -s -p 666
-----------------------------------------------------------
Server listening on 666
-----------------------------------------------------------
iperf3: error - unable to receive parameters from client: Connection reset by peer

The vm:

root@ks01:~# iperf3 -c 10.10.1.211 -p 666
iperf3: error - unable to send control message: Broken pipe