Default MTU 1440

On the Peplink Balance the default MTU is set to 1440. I am sure there is a very good reason for.

I know that the fiber connections I have has a MTU of 1500 and the ADSL connections a MTU of 1492. Everything is working fine with the default MTU of 1440 but should I change to 1500 and 1492? Theoretically there should be less fragmentation and increasing speed but maybe there is a good reason to stay with 1440.

Can someone explain?


Hi Marco,

The default setting of 1440 is to accommodate for the different quality of ISP connections from around the world. If your connections work good at 1500 & 1492, I recommend to set them as such.

Hi Marco,

Tim is right that 1440 tends to be a safe bet for most ISPs we see out there, and that you can fine tune that if you want to by determining the best MTU setting for your current ISP and connection.

There is a good guide here about how to determine the best MTU for your connection/configuration using the ping command with different fixed packet sizes here.

1 Like