gvisor: Operation timed out when using iperf3

Hi everyone,

I am experiencing a connectivity problem when using iperf3. I am booting a docker container with the following cmd: docker run -dit --name alpine1 --runtime=runsc -p 52022:22 -p 42022:5201 alpine ash

After configuring SSH and few other things, I am able to SSH into the container from the remote machine, no problem. However, when I start an iperf3 server inside that container and try to run the client on a remote host, it just hangs and timeouts.

From the client side I cannot see any output: iperf3 -c 10.90.36.40 -p 42022 -V

From the server side, I see:

 iperf3 -s

-----------------------------------------------------------

Server listening on 5201

-----------------------------------------------------------

iperf3: error - unable to receive parameters from client: Operation timed out

This exact setup works perfectly with the default docker runtime.

Host system: 4.15.0-47-generic #50-Ubuntu SMP Wed Mar 13 10:44:52 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux Docker version 18.09.2, build 6247962 runsc version release-20190304.1-112-g4209edafb6a9, spec: 1.0.1-dev iperf 3.0.11