New modem/router has been connected to iiNet for 12 hours now without a dropout. That's 11 hours longer than the old modem had managed at any time since they "upgraded" their infrastructure the weekend before last.
Fingers crossed.
If anyone needs a
Linksys BEFW11S4 wireless router and/or an Alcatel Speedtouch Home ADSL modem (which does work, just not with 1500Kbit ADSL on iiNet's new infrastructure), they're going cheap. :-)