Java - Can't connect zeroc.Ice : com.zeroc.Ice.ConnectionRefusedException : error = 0

Question

I have an error while trying to connect my server to another where Mumble is installed. My servers run with Dockers but all my addresses are linked together in a private network.

Here is the method I use for the connection:

public static CompletableFuture<MumbleConnectionHolder> connect(String iceHost, int icePort, String currentHost, String writeSecret) {
    Properties[] properties = new Properties[1];
    InitializationData[] data = new InitializationData[1];
    Communicator[] communicator = new Communicator[1];
    String[] metaProxyUrl = new String[1];
    MetaPrx[] metaPrx = new MetaPrx[1];
    String[] oaProxyUrl = new String[1];
    ObjectAdapter[] objectAdapter = new ObjectAdapter[1];

    return CompletableFuture.supplyAsync(() -> {
        properties[0] = Util.createProperties();
        properties[0].setProperty("Ice.ImplicitContext", "Shared");
        properties[0].setProperty("Ice.RetryIntervals", "0 10 30 60");
        properties[0].setProperty("Ice.Trace.Retry", "1");

        data[0] = new InitializationData();
        data[0].properties = properties[0];

        try {
            communicator[0] = Util.initialize(data[0]);
            if (writeSecret != null) {
                communicator[0].getImplicitContext().put("secret", writeSecret);
            }

            metaProxyUrl[0] = String.format("Meta -e 1.0:tcp -h %s -p %d", iceHost, icePort);
            metaPrx[0] = MetaPrx.checkedCast(communicator[0].stringToProxy(metaProxyUrl[0]));
            oaProxyUrl[0] = String.format("tcp -h %s", currentHost);
            objectAdapter[0] = communicator[0].createObjectAdapterWithEndpoints("Callback.Client", oaProxyUrl[0]);
            objectAdapter[0].activate();

            return new MumbleConnectionHolder(communicator[0], metaPrx[0], objectAdapter[0]);
        } catch (Exception e) {
            throw new CompletionException(e);
        }
    });
}

And here is the error: