Configure Max Transfer Unit (MTU) size for the TCPIP stack
The default Max Transfer Unit (MTU) size for ethernet is 1500 bytes, if using a network with a different MTU size, then one should make sure to configure MTU in Windows to avoid packet fragmentation and loss of VPN connections.
- Adapter MTU:
[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \Tcpip \Parameters \Interfaces \{Adapter-id/GUID}]
MTU = 1500More Info MS KB900926
- Point-To-Point Protocol (PPP) MTU for Modem DialUp Networking(DUN) or over Ethernet (PPPoE):
[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \NdisWan \Parameters \Protocols \0]
ProtocolType = 0x00000800
PPPProtocolType = 0x00000021
ProtocolMTU = 1500More Info MS KB283165
More Info MS KB826159More Info MS KB283070
More Info MS KB317496 - Virtual Private Network (VPN) Tunnel MTU:
[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \NdisWan \Parameters \Protocols \0]
ProtocolType = 0x00000800
PPPProtocolType = 0x00000021
TunnelMTU = 1400More Info MS KB826159
Related Configure Max Transfer Unit (MTU) in Windows NT4
Related Configure Max Transfer Unit (MTU) in Windows Vista/2008/7