Thanks for the info! I think the default gateway is missing in those pictures because the modem didn't have a PPPoE session there (since it's in bridged mode in those pics). The pc had the actual PPPoE session going.
I remember the DSL guy saying the technology is supposed to be exactly like you said: 1 pair and you're good no matter what. But he said they were doing it a little differently (for whatever reason) so it wouldn't work for me exactly like that. Maybe that's why this modem is so flakey is because of their non-standard setup. But the ZyXEL seems to use the same chipset (broadcom) as the DDR2200... and the interface and options are very similar. It looks like each vendor took a base config and tweaked it the way they wanted it... but underneath the hardware is the same or very similar.
So far I've seen the following modems support G.998.1: P-663H-51, P-663HN-51, Comtrend Nexuslink 5631, DDR2200. I'd like to try them all, but they aren't cheap. I bought this one knowing I could return it if it didn't work.
The reason I'm doing all this is because at my house... and my parents house... if I max the download for a long time, the DDR2200 does a hard lockup and has to be rebooted. It happens quicker at my house, but the same issue happens at both houses, and they are pretty far apart. Same town, but still far apart. After 2-3 months of trying things now (swapping cards, swapping lines, replacing modems, etc) the phone company is still unsure as to what the problem is. I am almost convinced it's the modem as I can't even get in to it or ping it when the DSL does down. It's gotta be a hard lockup at the modem.
Ah well, I will do more testing at my parents house and see what I come up with. If it's the same issue I'll RMA the modem for another one just to be sure it's not faulty. And if the same issue happens I'll get a refund and probably just wait for VDSL which is 1-2 months away in my area