I got the new 7800n router on Saturday and everything seems fine so far - notebook and sons iPhones connect to wireless right away and seem to stay connected.

For me, it's far better getting this other model than tinkering around with a new router when it's not working as it should.
Seems some people get this wireless problem, others not.
Hopefully whatever causes it will get resolved by Billion before I need another!

DPD collected the 7800DXL for return to Amazon, and although tracking is not showing it delivered yet, I'm hoping that goes without a hitch.