ADSL modem slow in PPPoe mode
 

Hi,
I have Linuxmint 13 and connect to internet using ADSL modem cum router. The modem is configured to connect in PPPoe mode. Off late the connection was slowing down. So I configured the Modem in Bridge mode and connect using Network Manager. Now the speed is back to normal. Even after resetting the modem PPPoe mode is slow.

How can we diagnose this problem?

Try to change the MTU value on your Linux network interface and/or on your modem interface.
PPPoE often requires this procedure.
Default value is 1500. Try 1492 or 1400.

Thanks @Lexus45. I tried already but not much success. Looking for some tools/ways to find out the real problem.