Draytek Vigor2120n-plus User Manual page 290

Available settings are explained as follows:
Item
User account and
Authentication
Allowed Dial-In Type
Vigor2120 Series User's Guide
Description
Enable this account - Check the box to enable this
function.
Idle Timeout- If the dial-in user is idle over the limitation
of the timer, the router will drop this connection. By
default, the Idle Timeout is set to 300 seconds.
PPTP - Allow the remote dial-in user to make a PPTP VPN
connection through the Internet. You should set the User
Name and Password of remote dial-in user below.
IPsec Tunnel - Allow the remote dial-in user to make an
IPsec VPN connection through Internet.
L2TP with IPsec Policy - Allow the remote dial-in user to
make a L2TP VPN connection through the Internet. You
can select to use L2TP alone or with IPsec. Select from
below:

None - Do not apply the IPsec policy. Accordingly,
the VPN connection employed the L2TP without
IPsec policy can be viewed as one pure L2TP
connection.
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