So an extra question is... can these routers with 'guest WiFi' networks be so configured, such that firewall ports opened for the benefit of guests continue to be blocked as regards the 'secure' LAN?
I've never investigated the feature, so I can't answer the question, but here's a link to the 7800DXL spec, and there's a link to the full manual at the top right: http://www.billion.uk.com/product/wireless/7800dxl.htm
Thanks for that, I shall indeed sit back and have a browse at the manual. Shouldn't take long, it's only 270 pages.
I've now remembered however that, even if the firebrick would do the job of creating a DMZ, on a home network you run into the problem of where to do the Nat, the router or the firebrick?
Many home routers, of course, offer a DMZ host to be configured, and specific port forwarding is also a related solution. But as far as I know such features fall far short of a true DMZ.
Maybe I should start a new thread on home DMZ though, or resurrect an old thread, I didn't mean to steal Burakkucat's 'grotto' thread. But I do love the look of that Billion user manual. I definitely now feel a burning need for both a firebrick and that billion router too.