Thanks. Turns oiut that the address for my router was 192.168.1.254. When I got there found no way to add the USB port/drive. Threw in the towel and called U-verse support. Was told that that port is for AT&T use only, e.g., in upgrading firmware. I wonder about that but am accepting it for the moment.
I'm trying to set up an inexpensive backup system that would be accessible wirelessly. In addition to the USB drive I have two daisy-chained firewire drives that I connect to via a thunderbolt adapter. Id love to find a router that has onboard storage [hd or ssd], a couple of usb ports, and a couple other ports [firewire or thunderbolt]. Imagine the latter is unlikely. LaCie was making something called they Wireless Space that had the other features, but apparently they've stopped; it's not even available on Amazon.
Last, a question, that put to U-verse technical support, the answer to which I also wonder about: Could I replace the router provided by at&t with another? They said no. Really?
Thanks for the generouse responses.
Sincerely,