Digi TransPort User Manual page 265

IPsec parameters
L2TP n parameters
Act as a listener only
When checked, this checkbox causes the router to NOT actively attempt to establish an L2TP
tunnel. In this mode it will only use L2TP if the remote host requests it. When unchecked, the
router will actively try to establish an L2TP connection with the remote host.
Enable Server mode
When checked, this checkbox causes the router to act as a L2TP server.
Initiate connections to a.b.c.d
The value in this text box specifies the IP address of the remote host, such as the device that
will terminate the L2TP connection.
Use a.b.c.d as a backup
It is possible to specify a backup remote L2TP host server using this parameter. The text box
contains the IP address of the remote server to use.
Digi TransPort User Guide 265