Set Up the Configuration Provisioning for L2TP rule

Go to Configuration → VPN → IPSec VPN → Configuration Provisioning, click Add button create rule and select L2TP rule which you would like to provisioned.

Configuration → VPN → IPSec VPN → Configuration Provisioning → Add

Use your IOS device to get L2TP configuration from device

Use your IOS device and Safari access to device and login by normal user which you setup in provision. (e.g. https://192.168.1.1). And then click "L2TP" button to download configuration.

Enter your IOS device password, and then click Install button to install it.

Enter IKEv1 user name and password after installed configuration.

After these steps you can find the L2TP rule appears on your IOS device. (Settings → General → VPN → L2TP_Connection) And you can try to connect IKEv1 tunnel on your IOS device.

Test the Result

On your IOS device, you can go to Settings → General → VPN → L2TP_Connection and click Connect button, check if your VPN tunnel is establish or not.

What Can Go Wrong?

1. This function is only support for IOS 9.3 or above version.
2. When downloading configuration, must use Safari to access device.
3. Please make sure assigned pool IP address avoided it has overlap to any subnet.