Sitecom WLM-5501 - Firewall Protection Configuration; Firewall and SPI Enable;Disable

14 Firewall Settings
The Broadband router provides extensive firewall protection by restricting
connection parameters, thus limiting the risk of hacker attacks, and defending
against a wide array of common Internet attacks. However, for applications that
require unrestricted access to the Internet, you can configure a specific
client/server as a Demilitarized Zone (DMZ).
Firewall
Parameter Description
Firewall Enable or Disable the firewall
SPI
Enable or Disable the firewall (Warning: If you
enable SPI, all traffic initiated from WAN will be
blocked)