う〜ん やはりだめでした…
下記設定なのですが、つっこみどころがあったらお教えくださいませ。

ip route default gateway pp 1
ip lan1 address 192.168.0.1/24
pp select 1
pp always-on on
pppoe use lan3
pppoe auto connect on
pppoe auto disconnect off
pp auth accept pap chap
pp auth myname ****** ******
ppp lcp mru on 1454
ppp ccp type none
ip pp address **.**.**.**/32
ip pp mtu 1454
ip pp secure filter in 1
ip pp secure filter out 1
ip pp nat descriptor 1
pp enable 1
ip filter 1 pass * * * * *
nat descriptor type 1 masquerade
nat descriptor address outer 1 **.**.**.**
dhcp service server
dhcp scope 1 192.168.0.3-192.168.0.254/24
dns server **.**.**.**
dns private address spoof on

もう一度最初からやってみる…