Code:
Break On
Dim $BaseKey, $Key, $Value, $RC
$BaseKey = 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces'
For each $Key in ArrayEnumKey($BaseKey)
  If AScan(ArrayEnumValue($BaseKey+'\'+$Key),'MTU')<>-1
   'Value ['+ReadValue($BaseKey+'\'+$Key,'MTU')+'] in Key ['+$Key+']' ?
;   $RC = WriteValue($BaseKey+'\'+$Key,'MTU','1400','REG_DWORD')
  EndIf
Next
_________________________
Give a man a fish and he will be back for more. Slap him with a fish and he will go away forever.