In most MDM configuration, there will be two setting to configure for VPN configuration: Packet Tunnel or App Proxy.
- Packet Tunnel is referring to L3 Tunnel
- App Proxy is referring to L4 Tunnel
For L3 Tunnel, packet tunnel would be recommended
For L4 Tunnel (Per-App or FQDN Split tunneling scenarios), app proxy would be recommended.
Known Limitations with iOS:
Apple Technical Document: