Running server and clients in GNU Screen terminals works unpredictably

[Spraitazz]

Describe the bug

Hi, I am running flwr 0.18.0 from pip on Ubuntu 20.04.4 LTS. I can sometimes get flwr to work, running the server on one GNU Screen terminal and 3 clients on other 3 terminals.

I am using the basic setup, running the server with fl.server.start_server(config={"num_rounds": 100}

and the clients with fl.client.start_numpy_client("[::]:8080", client=cl)

if I kill the server (ctrl + c), not all of the clients return the "status = StatusCode.UNAVAILABLE details = "Socket closed" message.

This is an issue only with GNU Screen, it does not happen using normally launched separate terminals.

Steps/Code to Reproduce

I am using the basic setup, running the server with fl.server.start_server(config={"num_rounds": 100}

and the clients with fl.client.start_numpy_client("[::]:8080", client=cl)

Expected Results

Not sure if there should be a difference between using GNU Screen and not.

Actual Results

FL does not start, not enough clients (not all 3) connect succesfully, even though the clients ALL log the following:

INFO flower 2022-04-13 15:02:46,474 | connection.py:102 | Opened insecure gRPC connection (no certificates were passed) DEBUG flower 2022-04-13 15:02:46,475 | connection.py:39 | ChannelConnectivity.IDLE DEBUG flower 2022-04-13 15:02:46,475 | connection.py:39 | ChannelConnectivity.CONNECTING DEBUG flower 2022-04-13 15:02:46,476 | connection.py:39 | ChannelConnectivity.READY