Q-Tec 584AA ADSL Modem: can't close outside port!

I've just bought a Q-Tec 584AA ADSL Modem & 4 Port Router for my family,
and moved them off the BT openworld USB modem and onto the Q-tec. I've
got it configured and working ok, with just one minor glitch: I've told
it to keep the http config interface open on the *inside*, and not the
outside, and yet after repeated attempts of saving this setting and
reloading the modem, the outside port is still open! This is very
frustrating, as I really don't want a port open to the outside world,
much less a configuration http port... I've changed the default port and
password to something different, so I won't get default hacked, but I
really want to shut that port. Anyone have experience with the same?
I'd try shutting down the inside port as well to see if that helped, but
then of course I can't configure the thing myself! (unless there is
another way of configuring it I don't know about?)

Also, this hardware suffers the "stupid defaults" disease. Warning to
anyone configuring a Q-tec: first thing you should do is shut off
*outside* FTP, TELNET and HTTP access, which is enabled by default!
<shakes head> What is it with the designers of modems/routers? You think
they would know that defaulting to 'open' is a very very bad idea....

thanks,
alex

p.s. I scanned my own IP using www.grc.com's Shields up, which is very
handy when you need to check the security of your firewall etc.