Solved Changing MTU value.

brummyfan

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Hi,
I am trying to change my MTU value, after changing in cmd(admin) it says "Ok" but when I reboot, the value switches back to the default value(1500), could someone help me change it to the value(1492) I have set in my router please. Thanks.
 

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I was under the assumption that the MTU was strictly a router setting. Is this not so? If not, where in the OS would it be located?
 

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You haven't mentioned which methods you have already tried for this?

To see the current MTU values, elevated command prompt > netsh interface ipv4 show subinterface

To change wireless MTU > netsh interface ipv4 set subinterface "Wireless" mtu=xxxx store=persistent

For wired connections > set subinterface "Local Area Connection" mtu=xxxx store=persistent

Or try > nestsh interface ipv4> set subinterface "Local Area Connection" mtu=xxxx store=persistent

If you need to mess with the MTU values it' likely that something else is causing the problem.
 

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Thanks guys, I tried wireless MTU setting: netsh interface ipv4 set subinterface "Wireless" mtu=xxxx store=persistent
I am trying to change the MTU because I have found out the optimum value for my router is 1492, can I leave the MTU value in OS as default?
 

My Computer

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  • OS
    Win 8.1
    Computer type
    Laptop
    System Manufacturer/Model
    Acer Aspire E1-571
    CPU
    i5-3230m
    Motherboard
    Acer Type-2
    Memory
    8GB DDR3 1333MHz
    Graphics Card(s)
    Intel HD 4000
    Sound Card
    High Definiton Audio Device
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    Generic
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    1366x768
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    Samsung 850 Pro 256GB
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I've never changed the MTU value in either the router on the OS and mine runs fine.
 

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    G-Skill 8 GB PC 8500
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if you really want to change MTU, first you need to evaluate what is the optimum. Never assume arbitrary correct parameter.
1) start with
ping www.google.com -f -l 1492
steady decrease value by 10 until no packed is fragmented - see picture
MTU evaluation.png

I would not bother though. I does not matter what target you will ping of course as long as it is pingable. MTU value change makes sense only if you have DSL connection and it may affect upload speed. Before and after each change run network speed test to see if these is any improvement or degradation of network performance. One more thing actual MTU value to enter equals highest not fragmented MTU + 28
 
Last edited:

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Thanks guys, I tried wireless MTU setting: netsh interface ipv4 set subinterface "Wireless" mtu=xxxx store=persistent
I am trying to change the MTU because I have found out the optimum value for my router is 1492, can I leave the MTU value in OS as default?

This is a pseudo science at best and in most cases will make no difference.

Network speed tests typically have to much inherent variation to either prove or disprove if changing the MTU actually worked or not.
 

My Computer

System One

  • OS
    Windows 8.1 Pro WMC
    Computer type
    PC/Desktop
    System Manufacturer/Model
    Home built
    CPU
    Q9650 @ 4.05 GHz
    Motherboard
    Gforce 780i SLI FTW
    Memory
    8GB Gskill DDR2 1200Mhz
    Graphics Card(s)
    GTX-480
    Sound Card
    Asus D2 Xonar
    Monitor(s) Displays
    HannsG
    Screen Resolution
    1680x1050
    Hard Drives
    Gskill 120GB SSD
    PSU
    Thermal Take 1000watts
    Case
    Thermal Take Xtreme
    Cooling
    9 fans air cooled
    Keyboard
    G15 logitech
    Mouse
    G9 logitech
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    50mbps
shrug, why then you even post it? As I mentioned MTU change affects only DLS users and only uploads. Not to mention that this will have more impact in the countries with better telecommunication infrastructure (than US). He is from England so he may see some improvements in specific conditions. If he runs several tests and gets average upload improvement of meaningful value then good for him. Personally I would not bother, but for game players this may be helpful (if it works at all).
 

My Computer

System One

  • OS
    windows 8.1
    Computer type
    Laptop
    System Manufacturer/Model
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    CPU
    i7-4800MQ
    Memory
    32GB
    Graphics Card(s)
    nVidia GeForce GTX 770M
    Browser
    Enhanced Protected Mode IE/protected mode Firefox
    Antivirus
    nope
    Other Info
    OpenNIC/DNSCrypt/VPN/EMET
Thanks chev65 & Michal for the contributions, I take your advice and leave as it is :D
 

My Computer

System One

  • OS
    Win 8.1
    Computer type
    Laptop
    System Manufacturer/Model
    Acer Aspire E1-571
    CPU
    i5-3230m
    Motherboard
    Acer Type-2
    Memory
    8GB DDR3 1333MHz
    Graphics Card(s)
    Intel HD 4000
    Sound Card
    High Definiton Audio Device
    Monitor(s) Displays
    Generic
    Screen Resolution
    1366x768
    Hard Drives
    Samsung 850 Pro 256GB
    PSU
    Generic
    Keyboard
    QWERTY
    Mouse
    ELANTECH Touchpad
    Internet Speed
    12.68Mbps
    Browser
    IE11
    Antivirus
    Windows Defender
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