D-Link AC1200 User Manual page 17

Section 3 - Configuration
Auto-reconnect:
The device will automatically reconnect to your PPPoE connection.
Enabling this option will disable the NAT function of the DWR-118,
NAT disable:
allowing it to act as a link for your devices to your Internet
connection, but without routing functions.
Click Apply to save your settings, or Refresh to revert to your
previous settings.
D-Link DWR-118 User Manual 13