Alright, well since you're on DEX you can still connect using CCAPI. Just download this:
You must login or register to view this content. and install it onto your PS3 and connect with your PS3's IP address. But if you want to simply connect using "DEX" Then you have to make a wired connection with your PS3 and Computer/Laptop. So what you have to do is have a ethernet cable going from your PS3 to Computer, and on your computer you want to share your computer's connection with your PS3's. To do this, look at the bottom right of your computer, and you see the little network bar?
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Right click on it and click "Open Network and Sharing Center", then once you've got that opened, click "Change adapter settings" on the right side, and now right click on your connection , click properties and then click the second tab and share the connection with "Local Area Connection", now go onto your PS3 and try setting up a wired connection, put everything as automatic. After you've got that, figure out your PS3's IP Address and go into target manager and make sure when you're adding it that you select it's target type to be "Debugging Station".