No data connection after ios4 upgrade on iPhone 3GS
I have an iPhone 3GS that was running the 3.1.3. Yesterday ios4 was released from Apple, so I decided to do the free upgrade. Everything went OK and I didn’t realize I had a problem due to my constant wifi connections at work and at home. But today when I was at lunch, I noticed that my 3G cellular data connection was not working. No mail, no Sarari web browsing, nothing. I could make and receive phone calls and txt messages, but that was it.
I had the 3G icon in the top left corner of the screen but I could not check mail or browse the web in Sarari. I tried rebooting, disabling and re-enabling the data connection, even tried resetting the network settings but none of that fixed the issue. Wifi would work without a problem, but if not on wifi, none of the above would work.
I connected my phone to my computer and used the iPhone configuration tool from Apple to open the device console log. From there I found errors and warnings related to the network config. A few Google searches later I found some threads on the apple support forums with users complaining of the same issues I was having. Someone in one of the forums suggested the issue could be caused by a glitch in the APN settings.
I then used the iPhone configuration tool from Apple to create a custom configuration profile where I manually input the correct AT&T APN settings. After applying this profile to my iPhone, I am now able to check mail, browse the web, etc. According to the support forums, this issue does not always occur, but there are a significant number of devices where this does occur. Apple and AT&T were reported to be at a loss relating to these issues when users would call for support.
At this point, the only other option for correcting this issue is to do a restore in iTunes and setup the phone as a new device, rather than restoring from backup. The downside here is the loss of SMS/MMS, call history, app data, etc.
The iPhone configuration tool is available from apple here: http://support.apple.com/kb/DL926
The correct APN settings for AT&T:
(All other settings under APN must remain blank)
I hope this information will be helpful to someone.