Options

Backup DNS	Backup DNS (1) IP Address: ... Backup DNS (2) IP Address: ... These DNS (Domain Name Servers) are used only if the primary DNS is unavailable.
TFTP	Enable Firmware Upgrade using TFTP
UPnP	Enable UPnP Services   Allow configuration changes through UPnP   Allow Internet access to be disabled
MTU	MTU (Maximum Transmission Unit): (1..1500) bytes This setting only affects PPPoE ,L2TP and PPTP connections.