smeserver-base/root/etc/e-smith/templates/var/service/wan/pppoe.pppd.conf/mtu

{
  $OUT = "";
  my $inkernel = "yes"; #$pppoe{InKernel} || "yes"; # we force inkernel for performance
  if ($inkernel eq "yes")
  {
    $OUT = "mtu 1492";
  }
}