How to Fix the 'PDP Authentication Failure' Error
What causes this error
The "PDP authentication failure" notification indicates that your device cannot establish a data connection with the carrier network. The most common reasons include incorrect APN details, zero remaining data balance, connecting to an unsupported roaming network, or a local network configuration glitch.
Step 1. Initial settings check
Verify APN (Access Point Name) settings:
Open the Unilink app, go to My eSIMs > Details > eSIM Installation, and check the APN requirements for your destination.
On your phone, navigate to Settings > Cellular (or Mobile Data) > select Unilink eSIM > Cellular Data Network.
Enter the APN value in lowercase letters as a single word (leave the Username and Password fields blank unless specified otherwise).
Check your data balance and plan validity:
Make sure under the My eSIMs tab that you still have active high-speed data remaining and that the package has not expired.
Confirm connection to a supported network:
Ensure your phone is connected to the partner carrier specified in your plan details. If needed, select the network manually in your cellular settings.
Step 2. Reset network settings (if the issue persists)
If the parameters are configured correctly but the error continues, reset your network settings to clear system cache conflicts:
For iOS (iPhone / iPad):
Go to Settings > General.
Scroll down and tap Transfer or Reset iPhone > Reset.
Select Reset Network Settings and confirm.
Restart your device.
For Android:
Go to Settings > General management (or System) > Reset.
Select Reset network settings (Reset Wi-Fi, mobile & Bluetooth).
Restart your phone.
Important: Resetting network settings deletes saved Wi-Fi networks and passwords, Bluetooth pairings, and VPN profiles. Your personal data, photos, apps, and contacts will not be affected.
What to do if the problem remains
If internet access is not restored after restarting your device, an agent will check the line activation status on the carrier side.