1801 is way too slow

i.cloud

I have a Cisco 1801 and the internet speed is just too slow comparing to my old Cisco 837. Here is my 1801's configuration:

interface ATM0
 no ip address
 no atm ilmi-keepalive
 dsl operating-mode adsl2 
!
interface ATM0.1 point-to-point
 no snmp trap link-status
 pvc 0/35 
  encapsulation aal5mux ppp dialer
  pppoe-client dial-pool-number 1
 !
 
 interface Vlan1
 no ip address
 bridge-group 1
!
interface Dialer0
 ip address negotiated
 ip nat outside
 encapsulation ppp
 dialer pool 1
 dialer-group 1
 ppp authentication chap pap callin
 ppp chap hostname XXXXXXXX
 ppp chap password XXXXXXXX
 ppp pap sent-username XXXXXXXX password XXXXXXXX
!

interface BVI1
 ip address 192.168.1.1 255.255.255.0
 ip nat inside
!

Note that I have changed different dsl operating-mode but still the same.

Thanks for your help.

i.cloud

I upgraded the Alcatel firmware and it resolved this problem. Thanks.