QTcpListener cut the connnection when I'm trying to connect with public hostname.

[LaurentDuroisin]

Hi, I've configured a public hostname on no-ip, and then configured my box to redirect the port.

I've also configured the firewall to accept that connection.

But Qt is cutting the connection :

socket->connectToHost("monsite.ddns.net", 80); // On se connecte au serveur demandé

socket->connectToHost("monsite.ddns.net", 80); // On se connecte au serveur demandé

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I've started to listen on that port :

serveur = new QTcpServer(this);
    if (!serveur->listen(QHostAddress::Any, 50885))

serveur = new QTcpServer(this);
    if (!serveur->listen(QHostAddress::Any, 50885))

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Why is the Qt server cut the connection ?