Unity client connection to server(STOMP, SockJS)

Question

I used WebSocketSharp, but Socket ready state was 'Closed' after 'New'.

And Debug.Log was print "Disconnected from STOMP server" only.

Why Socket doesn't OPEN??????

        string socketUrl = GameURL.DBServer.PlayURL;// start with ws
        string accessToken = UserDataManager.Instance.AccessToken;

        WebSocket ws = new WebSocket(socketUrl);
        webSocket.SetCookie(new WebSocketSharp.Net.Cookie("Authorization", "Bearer " + accessToken));

        webSocket.OnMessage += (sender, e) =>
        {
            // Handle STOMP messages received from the server
            Debug.Log("Received message: " + e.Data);
        };

        webSocket.OnOpen += (sender, e) =>
        {
            // STOMP connection logic goes here (subscribe, send, etc.)
            Debug.Log("Connected to STOMP server");
        };

        webSocket.OnError += (sender, e) =>
        {
            // Handle connection errors
            Debug.LogError("WebSocket error: " + e.Message);
        };

        webSocket.OnClose += (sender, e) =>
        {
            // Handle disconnection
            Debug.Log("Disconnected from STOMP server");
        };

        webSocket.Connect();
    }

I expected Open Debug.Log.