There are lots of these ADSL modem/routers around, as TelecomNZ used to rent them out when ADSL was first available here.
So they are PowerPC based (CPU = MPC860SAR), and can use GDB? Interesting...
They support PinHoling.
Useful tips:
useful console commands: status show help (all commands for displaying info)
configure (to change settings)
They were replaced by the M1122.
2 pages link to M11: