Project works, but does not connect to freeboard.io

String ReadIncomingRequest()
{
    while(client.available()) 
    {
        ClientRequest = (client.readStringUntil('\r'));
        
        if ((ClientRequest.indexOf("HTTP/1.1")>0)&&(ClientRequest.indexOf("/favicon.ico")<0))
        {
          myresultat = ClientRequest;
        }
    }
  return myresultat;
}

Why does this function need to return a global variable?

(Why) (is) (the) (call) (to) (the) (readString()) (method) (wrapped) (in) (useless) (parentheses) (?)

    // Capture response from the server. (10 second timeout)
    long timeOut = 4000;

4000 milliseconds is NOT 10 seconds.

    //Writing data to local server
    client = server.available();

No, that is NOT what that code does.

    ClientRequest = (ReadIncomingRequest());

(More) (useless) (parentheses).

Why do you bother reading what the client asked for, when you intend to deliver exactly the same reply?

Inside the and tags you are supposed to have and tags.

I can connect to wifi but not to the freeboard server. Any suggestions?

Yes. "I can't connect" is useless information. The connect() method returned a value. That value obviously doesn't mean success, but it is not false, either. What IS it?