Change the Maximum Transmission Unit (MTU) Size (Windows NT/2000/XP)

This parameter specifies the Maximum Transmission Unit (MTU) for a network interface. By optimizing the MTU setting you can gain substantial network performance increases, especially when using dial-up modem connections.

MTU stands for Maximum Transmission Unit and in basic terms, it defines the maximum size of a packet that can be transferred in one frame over a network.

Open your registry and find the key below.

      System Key: [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\[Adapter ID]]
      Value Name: MTU
      Data Type: REG_DWORD (DWORD Value)
      Value Data: Default = 0xffffffff
Create a new DWORD value, or modify the existing value, called "MTU" and set it to equal the required MTU size in decimal.

Recommended Values

      576 - Dial-up Connections 
      1492 - PPPoE Broadband Connections 
      1500 - Ethernet, DSL and Cable Broadband Connections 
Restart Windows for the change to take effect.

Note: For Windows NT 4 the key is [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ Tcpip\Parameters]

Note: IP datagrams may span multiple packets. Values larger than the default for the underlying network will result in the transport using the network default MTU. Values smaller than 68 will result in the tranport using an MTU of 68.

        (Default) REG_SZ (value not set)  
        MTU REG_DWORD 0x000005dc (1500)