TP-Link TD-W9970 User Manual page 36

Click Advance, you can see the advanced selections for WAN Service Setup.
MTU (Bytes): Maximum Transmission Unit Size. Check this box then you can change the MTU

size. The default MTU
value unless required by your ISP.
Enable NAT: This technology translates the IP addresses of a local area network to a different

IP address for the Internet. If this modem router is hosting your network's connection to the
Internet, please select the check box. If another router exists in your network, you don't need to
select the option.
Enable Fullcone NAT:

Enable SPI Firewall:

firewall, or else without a firewall.
Enable IGMP Proxy:

multicasting on TCP/IP networks. Some ISPs use IGMP to perform remote configuration for
client devices, such as the modem router. The default value is disabled, and if you are not sure,
please contact your ISP or just leave it.
Get IP with Unicast:

support to enable this. When the router is connected right but cannot get IP, you can select this
box.
value is 1500 Bytes. It is not recommended that you change the default
It is a type of NAT. If not enabled, the default NAT will act.
A SPI firewall enhances network's security. Select the option to use a
IGMP (Internet Group Management Protocol) is used to manage
This is disabled by default. The minority of DHCP Server of ISP will not
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TD-W9970 User Guide