D-Link DIR-850L User Manual page 39

Section 3 - Configuration
DNS Servers: Enter the Primary and Secondary DNS Server Addresses (Static L2TP only).
MTU: Maximum Transmission Unit - you may need to change the MTU for optimal performance with your specific ISP. 1400 is the default
MTU.
MAC Address:
The default MAC Address is set to the Internet port's physical interface MAC address on the Broadband Router. It is not recommended
that you change the default MAC address unless required by your ISP. You can use the Clone Your PC's MAC Address button to
replace the Internet port's MAC address with the MAC address of your Ethernet card.
D-Link DIR-850L User Manual 34