PPPOE dialer issue on Cisco C2811

["Meftah Tayeb" <tayeb.meftah () gmail com>]

Hey folks
please can someone see this issue
i'm veery stuck on that:
i have a C2811 with ADSL line
created a dialer interface
assigned to a fast ethernet (fe0/0)
connected sucsessfully
nated my lan network (172.28.0.0/24)
the dialer is outside and my fe0/1 is inside
but i can access (ONLY) google services!
i guess is that a MTU issue?
if yes what should i use ?
tried 1492
1480
1500 and 1504
same hell at all.
here's my config:

    Meftah Tayeb
IT Consulting
http://www.tmvoip.com/ 
phone: +21321656139
Mobile: +213660347746


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