Вот поведение iperf3:
клиент:
root@lxc:~# iperf3 -c 10.243.2.1 -u
Connecting to host 10.243.2.1, port 5201
root@router:~# ip netns exec clients iperf3 -s
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 192.168.2.1, port 50288
[ 5] local 192.168.2.18 port 5201 connected to 192.168.2.1 port 58092
iperf3: error - unable to read from stream socket: Connection refused
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 192.168.2.1, port 50290
[ 6] local 192.168.2.18 port 5201 connected to 192.168.2.1 port 56574
iperf3: error - unable to read from stream socket: Connection refused
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
С чем это связанно?