I have 2Wire 3800HGV-B gateway (modem) and having trouble going thru its firewall for my IP cameras:

1. on the LAN side if IP cam is connected DIRECTLY to the gateway, say at port 81 then I can connect to it from the WAN side (http://wan_IP:81) but

2. if I connect the same IP camera via a pair of Powerline module ( because I have to put camera at a distance from the gateway where network cable can't reach); then I can see the camera from any PC on the LAN ( http://192.168.1.xx) but the same port 81 can't be connected from the WAN side ( http:// WAN_IP: 81)

It appears that the gateway is not letting me getting thru the power-line module,  may be the pair of power-line module with its own MAC address are not suppose to be transparent ?

Help, anyone?

Thanks