WebSocketBehavior callbacks not getting called

I'm using WebSocketServer in my Unity application, the WebSocketBehavior callbacks are not getting called, please find the code below,

public class CustomWebSocketBehaviour : WebSocketBehavior
{

    protected override void OnOpen()
    {
        Debug.Log("WebSocketBehaviour: Connection open");
        base.OnOpen();
    }

    protected override void OnMessage(MessageEventArgs e)
    {
        Debug.Log("WebSocketBehaviour: Message Received - " + e.Data);
        base.OnMessage(e);
    }

    protected override void OnError(ErrorEventArgs e)
    {
        Debug.Log("WebSocketBehaviour: Error occured - " + e.Message);
        base.OnError(e);
    }

    protected override void OnClose(CloseEventArgs e)
    {
        Debug.Log("WebSocketBehaviour: Connection closed");
        base.OnClose(e);
    }
}

private CustomWebSocketBehaviour webSocketBehaviour;

public void StartServer(IPAddress ipAddress, int port)
    {
        webSocketServer = new WebSocketServer(ipAddress, port);
        webSocketServer.AddWebSocketService<CustomWebSocketBehaviour>("/",HandleAction);
        webSocketServer.Start();
    }

void HandleAction(CustomWebSocketBehaviour obj)
    {
        
    }

Start with StartServer, AddWebSocketService, and HandleAction, then trace whether the WebSocketServer reaches Start and creates the registered service. Check the WebSocketBehavior callback lifecycle against the reported Unity setup; done means the relevant callbacks are observed for connection, message, error, and close events.