Thanks for the update! The first thing I'd check, if I were you, would be to take the modem out of bridge mode, connect it to your PS3, and see if you still get any disconnects (i.e. ruling out the modem as the cause). You mention that your Internet doesn't disconnect, so I'm guessing the router is dropping the wireless connection when it can't handle the amount of data being transmitted. If so, you'll have to check the settings on your router, or maybe even test with a different router.
Please keep us posted!