Thank you for posting regarding your firmware upgrade. You actually have the newest firmware on your printer. Just upgraded yesterday so have confirmed the differences. Reason: the 3-27-2014 is the date this firmware was released to the web. 2-24-2014 is the actual firmware datecode (always go by what is on your configuration sheet).
When you disconnect it from the network cable, are you able to connect the wireless via the control panel? Have you tried reinstalling the software via the wireless path to see if you can connect wireless this way?
Couple of suggestions that I am unclear if you have tried:
1. Restart your router. You started that you have unplug print and router and plugged them back in but am unclear if this means you power cycled your router.
2. Reinstall the Software and use the wireless route for setup.
The reason I am suggeting this is I just upgrade my firmware (via a USB cable) yesterday and have no issues with the printer immediately reacquiring the wireless address.