if you are refering to the blackberry client, I am aware of some connection drop offs on the demo.qlik.com site. My recommendation is to go into the settings of your blackberry client and uncheck connect via socket, check connect via http and change the port to 80 rather than 4747 and you will be able to connect using the demo site tunneler.
I have been told a new bb client is coming very soon that addresses this "switch to http" feature to allow it to work with both connect via socket & connect via http checked.
On the demo.qlik.com side, when we originally made the amazon elb for demo we only opened port 80 all the way through. Since we do not anticipate direct traffic to the qvs machine(s). I have been testing with a new elb that has port 80 and port 4747 open, hopefully this too will help address connection drops.