I got a unlocked 1.1.4 iphone. Some wifi connections I get don't work. It will have the 3 bars in the upper left corner showing I have a connection but when I go to use it. It says Safari can't open the page because it can't find the server.
Have you tried restoring it? Sometimes that'll do the trick.Just make sure you backup your files and you restore to 1.1.4 and not 2.0 **if you are planing on jailbreaking/unlocking**
I have the same problem and the answer is you router and the iPhone are not recognizing the same settings. You have to change the DNS, IP, Subnet stuff. I tried but it didn't work for me. Annoying problem.