My apologies to all those who kindly replied to my post on the above subject for not acknowledging those replies sooner. I was required to be away from the computer for a few days. Encouraged by some of those replies to do so, I re-configured the modem in Windows, using the instructions from the D-Link Australia site. I then switched into Linux and found that the changes did what I'd hoped (at least for now!). My thanks to everyone.