Grandstream and a Westell DSL modem

[abward]

I tried unsuccessfully last Saturday to hook up a GS HT502 at my sister's house. She has 1.5Mb DSL from AT&T (switching her to 7Mb Earthlink cable soon).

The Westell (I think 6100) DSL modem has a router and firewall built-in. Eventually I figured out that I needed to set the GS to be in bridge mode, to turn it's DHCP server off, and placed it behind the Westell, and in front of her wireless router (which has DHCP turned off). The GS was still not registering. I tried live support for VOIPo and the dude told me to try and pass through traffic on the Westell to the GS. I found an IP Passthrough setting in the Westell to do this and the GS registered okay.

So I said goodbye to the support dude. Silly me, I wanted to get rid of the tangled mess of the power cords of the GS and Westell, so I unplugged them. You guessed it: when I plugged them back in, I could not get the GS to register again.

I tried all kinds of stuff, including resetting devices and turning off DHCP and the firewall in the Westell, but could not figure out the magic combination again. By this time, the support dude at VOIPo had gone home.

So, please, how should I hook this thing up?

1. Westell (Bridged Ethernet mode, with firewall off, DHCP off) ---> GS (normal mode, DHCP on, Firewall on, enter PPPoE userid/password here) ---> Wireless router (DHCP off) ?
2. Westell (Bridged Ethernet mode, with firewall off, DHCP off) ---> GS (Bridged mode) ---> Wireless router (Normal mode, DHCP on, enter PPPoE userid/password here) ?
3. Westell (Normal mode, with firewall on, DHCP on, IP Passthrough for the GS, enter PPPoE userid/password here) ---> GS (Bridged mode) ---> Wireless router (DHCP off) ? This is what I tried already

Frankly, I am currently thinking there is something wrong with this GS. I asked for a PAP2-NT but did not get one.

Tomorrow is Saturday and I will try all this again....Thanks