This phenomenon is repeated with different modems on different machines.
It's better to compare them against other ISP's using the same hardware and ask for an explanation.
I once managed to get my ISP to admit they where blocking incoming traffic to port 80. ( borrowed a dailin account )
My ISP can only provide me with the error codes and when attempting to talk to Telecom my call is always forwarded to Xtra who decline to assist as I am not an Xtra customer. When Telecom designed its customer assistance service they obviously studied and implemented the plot of Franz Kafka's novel The Castle [1]
Your ISP admits there is a problem for older Mac's on there website and provides a dailin script. Perhaps you can ask them what the difference is.
Good luck! Col.
