This setup works with DGN2000, never tried it with DGN2200. You can test it though:
1. Access the web-user interface of the modem by typing
http://192.168.0.1 in the address field.
2. When prompted, enter “admin” for the username and “password” for the password (if you haven't changed yet the password for the interface).
3. Once logged in change the address URL in the address bar from:
http://192.168.0.1/setup.cgi?next_file=start.htm
to:
http://192.168.0.1/setup.cgi?next_file=mode.htm
4. This opens a hidden configuration page on router. Select 'Modem (Modem only)' and click Apply. This will convert the router into a simple ADSL mode. Router (Modem + Router) sets the device to modem-router mode.
5. After setting up the modem to Bridge mode, Basic Settings option is gone under Setup tab. You could still configure the ADSL settings though.
6. You can now connect the DGN2200 to your router or computer and setup for a PPPoE connection.