The real issue I can see is with your trading program and how it works. If the server has a keepalive connection (usually HTTP connection) with your IP address then you still need to connect again (as it needs to associate the new username with the new Ip address). i.e try watching a youtube video, while it is switching I wouldn't be surprised to find the video stop downloading and for you to hit the refresh button. Security in the program is another issue if it associates your logon with an ip address.