It sounds like you need to Port Forward your modem/router.....I can only find the speedstream 6520 instructions so when you log into your modem and it looks different to what is shown in the instructions let me know...
http://www.portforward.com/english/r...0/Limewire.htm
Also when you log in try using 10.0.0.138, that's Telstra's log in number...