The remote app worked fine, but since I restarted my iPhone, it can't connect to the Pinball game at all. It keeps saying "Lost Connection - Either the server shuts down or network connection broken". The Wi-fi network is still the same, and I changed nothing on my Macbook. I am really frustrated because I paid for the Deep Water Table!

OK I got it to work because I switched back to the original network environment which I used when I installed the game for the first time. This is still strange, because both environments have the same settings without unique proxy settings etc.
I am also having problems that the game sometimes becomes completely unresponsive and the flippers then react with a 5 or 10 seconds delay.

If you have the iPhone 4 (or iOS 4), try completely closing out the remote application by double-clicking your Home button and then closing it from the system tray. When you re-launch the remote app, it should then find your network again (if you've first launched The Pinball on your Mac).