your adsl is chap or pap? (authproto chap) check this... and enable the net.inet.ip.forwarding=1 in /etc/sysctl.conf.
check you resov.conf in /etc
Try this
1- vi etc/ppp/ppp.conf
2-
default:
set log Phase Chat IPCP CCP tun command
set redial 15 0
set reconnect 15 10000
pppoe:
set device "!/usr/sbin/pppoe -i fxp0"
disable acfcomp protocomp
deny acfcomp
set mtu max 1454
set speed sync
enable lqr
set lqrperiod 5
set cd 5
set dial
set login
set timeout 0
set authname
user@plusdsl.net #user
set authkey passwd_isp #passwd ISP
add! default HISADDR
enable dns
enable mssfixup
3-# vi /etc/hostname.fxp0
up
! /bin/test -f /etc/ppp/ppp.conf && /usr/sbin/ppp -ddial pppoe
#enjoy