Draytek 2750 manual Authentication, Advanced Settings

type, please specify the IP address and subnet mask for local network.

L2TP/IPSec –The range must not overlap the DHCP address range (if enabled), and must allow for at least one IP address. Example: 10.10.137.240-10.10.137.245. If you choose this type, please specify the IP address range for L2TP/IPSec mode.

Authentication	Shared secret – Type the shared secret manually and confirm it
	again. IPSec remote dial-in clients will use the given secret.
Advanced Settings	Phase 1 (IKE) - Negotiation of IKE parameters including
	encryption, hash, Diffie-Hellman parameter values, and lifetime
	to protect the following IKE exchange, authentication of both
	peers using either a Pre-Shared Key or Digital Signature (x.509).
	The peer that starts the negotiation proposes all its policies to
	the remote peer and then remote peer tries to find a
	highest-priority match with its policies.

Phase 2 (IPSec) - Negotiation IPSec security methods including Authentication Header (AH) or Encapsulating Security Payload (ESP) for the following IKE exchange and mutual examination of the secure tunnel establishment.

Vigor2750 Series User’s Guide 183