Try port forwarding for your Motorola, the instructions are here.
Port Forwarding for the Motorola SBG 900
Don't miss the step of setting up a static IP address first, or port forwarding won't work. There's a link to static IP setup within those port forwarding instructions.

LW's listening port, port in the 'manual port forward' box & port forwarded within the modem should all be the same number.

Thread will be merged with yesterday's thread on the same topic!