At first I thought it was my ISP, who was having service problems last night as well (and of course there's no tech support at 1AM), so I power-smacked the DSL modem and went upstairs to check the fire. However the DSL modem usually only eats itself about once every 2-3 weeks, and since I power-smacked* it last night already, I didn't think this would really help that much.
It didn't help any. So then, noticing that I was getting No Route to Host, I started suspecting that the problem could be local. Turns out I couldn't reach the NAT box (which is on the same local net), so I went and power-smacked that as well. Didn't help much. Stupid Netgear box was off-line or something, this time completely.
Well it turns out I don't really need that box any more since the DSL modem does NAT too, and it was somewhat of a jurry rigged situation (especially with getting inbound ports to work), so it was time to do massive damage. First I checked that the DSL modem was working (since I had only verified that the netgear box was not), with a handy direct link cable, that unfortunately pulled the featherweight DSL modem off of the speaker tower where it currently lives, but as it seems the box is basically empty (based on its weight), it was no worse for its trip to the floor.
So after confirming the DSL was working, I reconfigured it to talk to my local network directly 192.168.67.xx, duplicated the DHCP settings from the other box (have to leave room for the static address'd servers), and restarted it. Unfortunately, its interface is unusually dumb for a stand alone appliance (or they have Microsoft update envy), and it only kept the server address setting, blowing away the port forwarding & DHCP settings. Several sequential resets later, it was configured properly and patched into the main switch (another Netgear -- don't ask).
And so we're alive. At least for the moment.
* PowerSmack - to rip the power adaptor out of wall, or yank the power connector on a device that is supposed to run forever and thus does not have a power switch.