PDP authentication failure sometimes displayed on iPhones when they try to connect to the data network but failed to do so because of incorrect settings configuration.
Follow the steps below to fix this error. After performing each step, please test to see if the issue is resolved.
- Toggle airplane mode. To do this, go to Settings and just turn on airplane mode for a few seconds, then turn it back off again.
- If you haven’t already, please try restarting your iPhone
- If the issue is still present, try resetting network settings*. To do this, go to Settings > General > Reset > Reset Network Settings.
* – this also resets Wi-Fi networks and passwords, cellular settings, Bluetooth device connections, and VPN and APN settings that you’ve used before.