I have a problem with a WebSocket connection that does not open on the client computer.
I explain the context:

• The Websocket server is running on a WinForm application installed on the client machine. It is accessible via the port 6060. and developed with the Nuget Fleck package. It is writed in c# like this :

X509Certificate2 certificate = new X509Certificate2(bytes, certPass);
server = new WebSocketServer("wss://0.0.0.0:6060");
server.Certificate = certificate;
server.EnabledSslProtocols = SslProtocols.Ssl3 | SslProtocols.Tls | SslProtocols.Tls11 | SslProtocols.Tls12;

• The client WebSocket is a basic web application and sends its requests to "wss:/mywebsocket.wss:6060/"
• A certificate is installed on the client machine to allow wss on this address. An entry is added in the hosts file to bind the domain name "mywebsocket.wss" to the address 127.0.0.1 .

This system works on many computers, but some of them have this problem.
No error message in the Websocket Server application when the client tries to open the connection. So for me, the connection doesn't have "time" to reach the server, it is stopped before.
The only thing observed in the chrome development tools is an entry like this one :

In the network tab we see an empty line like this one:

As if the websocket server was not started.
For me it is a problem of configuration of the computer which would block the connections towards the address or the port. But I could not find where it comes from.
We tried to disable antivirus completely, firewall, there is no proxy or VPN, we also disabled adblockers.
If you need more information don't hesitate to ask I will edit this post.
I will listen to all suggestions.