Cheule was you able to resolve this? I'm having the same problem (currently on Be*) driving me insane.
BeBox works flawlessly in bridge mode with the RT-N66U, The TP-Link 8817 doesn't work in bridge
EDIT:
I fixed this, Not sure if this will work for you but the issue you have sounds the same as mine... make sure you have also turned off/disabled the DHCP under 'LAN' Setting on the TP-Link TD-8817.
Interface Setup > LAN (Tab) > Disable DHCP
I turned it off and now my TD-8817 and RT-N66U are talking, Happy Days!
Edited by deleted (Wed 10-Apr-13 18:40:07)