I have the ZTE Warp, and currently use PDA.net for my internet access. I used to have FoxFi. The wifi hotspot never worked, my friend, who works for boost told me it is because, without rooting your phone you cannot access free hotspot with that phone, it doesn't support it. My bluetooth-DUN through FoxFi worked until a few days ago. It was a bit tricky to set up. But in the end I figured it out and it connected no problem. However, a few days ago I uninstalled it to try to find something better, and ended up trying to go back to FoxFi, only to recieve the message "This item is no longer supported by your carrier". My friend at Boost informed me that Boost Mobile has put a block on the app, so that people have to go to them for their hotspot needs.
For anyone having trouble with PDA NET, however... Until this morning, that wasn't working for me either. I was 5 seconds from pulling my hair out. It would connect with no internet access, and when I clicked "Diagnose and repair" I always recieved the same message. "There appears to be a problem with your DNS". I figured it out though. If you right click the PDA Net notification icon and hover over settings until the sub-menu appears, click hide tether usage, and deselect "Use google DNS".
That worked like a charm for me. I am not sure if you HAVE to hide the tether usage, but I did it anyway for good measure