DOWNGRADE ios7.02 to ios 7, unknow error 3194?

I was unlocked my iphone4s(Verizon) with IOS7, then i change my carrier to T-Mobile, all work's perfect, BUT after few days later, the service start unstable, after few days pass, about half month that i just changed my phone's carrier, the service was not work anymore, it back to Verizon. I bring my phone to T-Mobile store, they took me three days and still can't fix the issue. They tell me maybe i do something to the iphone and made the service not work. So I'm thinking about was i upgrade the ios7 to ios7.02 then make the service unstable? Then i try to downgrade it to ios7, but my computer keep shows the words: unknow erro 3194, but i already fix the hosts and upgrade the itune. I change to another computer try to downgrade, but the computer still shows me the unkown erro3194, what happened to it?! Anyone can help me to solve it? Please T-T

You might try to do a factory reset on the phone and hopefully that will work. It will likely be locked back to Verizon, though.

The problem with unlocking phones is that when you upgrade the software, often the "lock" is lost- especially if it was done by a third party and not be legitimate means.