Changing MTU on the gui does nothing

  • Hello,

    I tried this on pfSense 2.4.4-RELEASE-p2, did a fresh install too to make sure it isn't a config issue, but there is something strange showing up on my install

    On the interfaces / WAN, there are two fields: MTU and MSS

    I tested the changes using this site:

    I changed MTU to 1440, visit speedguide and nothing happens

    BUT if I change MSS to 1440, on speedguide the MTU field shows correctly, and MSS as 1400

    Is this a bug or I am understanding it all wrong?

    Thanks, have a nice day.

  • LAYER 8 Global Moderator

    @fernandodx-0 said in Changing MTU on the gui does nothing:

    understanding it all wrong

    Ding Ding Ding - you win yourself a cookie ;)

    Google mtu vs mss

  • Please enlighten me in one detail

    If I leave MTU on default, and on my Desktop Ubuntu I change my NIC mtu to 1440, speedguide shows the value I entered

    I revert my Desktop NIC to 1500, and change pfsense MTU on the WAN interface to 1440, no changes are seem on speedguide

    But if i change the MSS value of the WAN interface on pfSense, them the MTU value changes to 1440 on speedguide



    Why changing the MTU field on the gui din't show on speedguide, but MSS did actually reflect the value I entered for MTU?


  • LAYER 8 Global Moderator

    Because they are completely different things.. Again google mtu vs mss..

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