That was actually the first thing I did. I unplugged power to both the router and the modem, plugged the modem back in (thus making it the "...first thing" ) then the router.

Tony said to mention one other complicating factor. The topography is actually a little bit more complex than I mentioned, in that the wireless signal from my router goes downstairs to my neighbor into a second "repeater" WRT54G which then sends the original signal from my router to her devices. (Mark Lord set that up for me.) My house is so overbuilt with steel and concrete that a wireless signal will not propagate through the floor, so I send my wireless signal line-of-sight to the second router which then re-broadcasts it for her. She gets a five-bar signal, but her computer(s) won't connect to the internet any more than mine will.

I am at a loss here. It doesn't appear to be a hardware failure because the router works for everything except browser access to the internet (direct DOS ping, OOMA VOIP phone, printer, access to router settings all work) and to my [extremely] limited knowledge all the setup screens I can figure out how to access seem reasonable and are all exactly the same as when Mark "helped" me (he did all the work!) set up the repeater router (I kept careful notes!).

Perhaps it is time to take more drastic action -- click on the "Restore default settings" tab and then try and set up everything again from scratch. I'm a bit afraid to do that, since I would then be severing my only help lifeline.

tanstaafl.