Maximum Transmission Unit (MTU) of the WAN interface of the Firewall

Maximum Transmission Unit (MTU) of the LAN interface of the Firewall

The Maximum Transmission Unit size is the maximum size of an Ethernet frame being sent out through a network device. By default this value is 1500 bytes but on xDSL and cable connections this value is often lowered to achieve a more stable connection and/or better performance. Common values are: 1492 SDSL / 1460 ADSL / 1404 Cable. The MTU value is changed in increments of 8 bytes.

TIP: Change the MTU size after determining the optimum MTU size in order to prevent unnecessary fragmentation. Refer the following article to determine the optimum MTU value.

How can I test and change the MTU size of WAN interfaces? | SonicWall