I recently needed to configure a Cisco 837 to use bridge mode for my home ADSL. After a bit of troubleshooting I managed to get the correct config.

Then just make sure that your interfaces are not shutdown and you should be able to dial PPPoE with your WAN router from behind the 837.

interface Ethernet0
ip address 192.168.1.254 255.255.255.0
bridge-group 1
hold-queue 100 out
!
interface Ethernet2
no ip address
shutdown
hold-queue 100 out
!
interface ATM0
no ip address
no ip mroute-cache
no atm ilmi-keepalive
dsl operating-mode auto
bridge-group 1
pvc 8/35
encapsulation aal5snap
protocol ip inarp
!
!
interface FastEthernet1
no ip address
duplex auto
speed auto
!
interface FastEthernet2
no ip address
duplex auto
speed auto
!
interface FastEthernet3
no ip address
duplex auto
speed auto
!
interface FastEthernet4
no ip address
duplex auto
speed auto
!
ip classless
!
bridge 1 protocol ieee