Could not setup DSL connection on 1812K9

Hello, our Linux machine has to be replaced with 1812K9 and I should configure it. We use DSL connection. Currently, Linux box has two NICs. eth0 with

192.168.1.1 (LAN), eth1 with 10.0.0.1, to which xDSL modem (with internal IP 10.0.0.138) is connected. This Linux box connects eth1 to the internet using PPPoE with authentization with username/password (PAP) and performs NAT for eth0 making all our LAN connected to the net. The DSL modem is Alcatel Speedtouch 350,

formatting link

I tried to connect this modem to the FastEthernet0 on Cisco 1812K9 router and configure it using SDM wizard for PPPoE connection, but I failed. I was able to specify "PPPoE on, username, password, method PAP and IP address (which is assigned by remote PPP host). Unfortunatelly no connection is made. LEDs on the modem are blinking - it means there is some kind of activity, but it stops soon. No error message in Cisco log and no Internet connectivity is available.

What is very weird for me is that there is no place to enter IP address of the cable modem (10.0.0.138) and I suspect that IP address settings in the PPPoE connection wizard are bound to the internet connection itself, not to the connecting device. SDM documentation is very poor and not suggestive (like dialog box descriptions "IP address - enter IP address here") and since I have a lot of Linux (iptables, dhcpd, pppd) experience, I am new to Cisco and I was not able to get this connection working.

I would very appreciate pointing me to the how-to or documentation or direct IOS or SDM instructions or any other help. Thanks a lot.