The failures were coincident with thunderstorms and dimming lights. The unit has been outside and difficult to instrument. It’s now inside, hooked up to a serial cable and am awaiting the next thunderstorm. Being SW Florida and this time of year, it shouldn’t be long.
Searching found lots of complaints about recovering from low line voltage. Some of the discussion involved hooking up a LiIon and LiPo battery to the charger that is already on the board. Others suggested that the problem was noise on the serial rx line during bootup that caused redboot to stop booting and wait for console input. I’ll post a followup when I know more.
I am using a wifi usb dongle and the RTL8192CU driver. The driver has been rock solid since I shut off aggregation. I still haven’t heard anything from the linux-wireless list.