1) You have a server on the LAN side of your network2) You want to access the server using the WAN IP address from a device also on the LAN side of the networkIf you turn this off, it will allow you to access the server on your local network using the WAN IP address.If you turn it on, it will block access using the WAN IP, but obviously still allow by using the LAN IP.
This is primarily for testing servers on your network using their WAN addresses or names without using a computer that is separate from your LAN. Another name for this functionality is local loopback.
Okay tx fellahs. I'll leave it checked. I just transfer files with the PC's and share the net access. --Anyone but the lying and thieving Liberal Party. Vote the criminals out!