When I was using a Thomson BE Box in bridge mode with my Draytek 2820 doing the routing I had port one of the Thomson conected to the WAN 2 input of the router and a second cable connected to port two (I think) of the Thomson connected to one of the four LAN outputs of the Draytek.
It then quite quite happily recognised this and 192.168.1.254 gave me the login screen of the Thomson (the Draytek runs as 192.168.1.3 for historical reasons).
The Thomson is a pile of **** so I ditched it and connected the Draytek diirectly to the ADSL again.
Ex <n>ildram , been to SKY MAX - 15,225 Download
Now with BE Unlimited - 21,000 Download 1,200 Upload! Never happier!