Not browsing with D-Link 300T

Platform = Mac
OS = 9.2.2
Modem = D-Link 300T Ethernet
Service Provider = Tiscali.it

Hi,

I have been two weeks since I got activated my DSL account but I have been able to browse only twice, one day.

I access to the router and I am able to check my configurations which have been double checked tens of times the Tiscali Support.

When they try to ping to my computer they won't have access. All the tests (dos - with windows xp) have shown that the packets won't reach my port.

I am suspecting of some sort of Firewall that it stopping them on the modem but I don't know how to change this setting.

Is there any of you who had the same problem and sort it out, or are able to suggest a solution ?

thanks in advance