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CENTRIA WNDR4700/WNDR4720
Change the MTU Size
The maximum transmission unit (MTU) is the largest data packet a network device transmits.
When one network device communicates across the Internet with another, the data packets
travel through many devices along the way. If a device in the data path has a lower MTU
setting than the other devices, the data packets are split or “fragmented” to accommodate the
device with the smallest MTU.
The best MTU setting for NETGEAR equipment is often just the default value. In some
situations, changing the value fixes one problem but causes another. Leave the MTU
unchanged unless one of these situations occurs:
• You have problems connecting to your ISP or other Internet service, and the technical
support of either the ISP or NETGEAR recommends changing the MTU setting. These
web-based applications might require an MTU change:
- A secure website that does not open, or displays only part of a web page
- Yahoo email
- MSN portal
- America Online’s DSL service
• You use VPN and have severe performance problems.
• You used a program to optimize MTU for performance reasons, and now you have
connectivity or performance problems.
Note: An incorrect MTU setting can cause Internet communication
problems. For example, you might not be able to access certain
websites, frames within websites, secure login pages, or FTP or
POP servers.
If you suspect an MTU problem, a common solution is to change the MTU to 1400. If you are
willing to experiment, you can gradually reduce the MTU from the maximum value of 1500
until the problem goes away. The following table describes common MTU sizes and
applications.
Table 3. Common MTU sizes
MTU Application
1500 The largest Ethernet packet size and the default value. This setting is typical for
connections that do not use PPPoE or VPN, and is the default value for NETGEAR
routers, adapters, and switches.
1492 Used in PPPoE environments.
1472 Maximum size to use for pinging. (Larger packets are fragmented.)
1468 Used in some DHCP environments.