So the system has an onboard ethernet, 802.11a PCI and 802.11g PCI (plus usb ethernet for uplink); when I bridged g+ethernet and then set up a as a different range with different dynamics, the dhcp server wanted to serve a single range of dynamics on both interfaces (the g/eth bridge, and the a), which of course resulted in nonroutable addresses on one of the nets.
While reconfiguring I inadvertantly bridged the a net to the g/eth net. It works, including over a reboot. Beats the heck out of me. But it's been working for over a month.