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Will changing the MTU be a problem?

  1. Nov 17, 2011 #1


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    I've had this problem here for a while and think I've found the reason "why".


    Evidently there are other that have had this problem. It appears the it's due to the Maximum Transmission Unit (MTU=1505 in my case) is set too large for some sites to be able to handle . I understand that I can change the MTU value with the command: "netsh interface ipv4 set subinterface "Local Area Connection" mtu=1404 store=presistent" but I'm thinking this is my DSLs preset value and changing it would cause a connection problem. Any help would be appreciated.

    Last edited by a moderator: Apr 26, 2017
  2. jcsd
  3. Nov 18, 2011 #2


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    Okay. I guess what I was most worried about is not being able to reset it should I have a DSL connection problem. So I had a chat with the tech support for my DSL service and learned that the MTU can be changed but they recommended that I contact one of their "live agents" before proceeding; which I will do.

    Thanks for your patients as I learn.
  4. Nov 20, 2011 #3
    you can determine your ISP's largest MTU value by pinging a website and giving your system the packet size you want to use for the ping

    in a dos prompt, execute the following command
    ping -f -l [MTUSIZE] [yourISPgateway]

    replace MTUSIZE with a number and yourISPgateway with the ip address of your ISP's gateway.
    the largest value that you are able to use is your MTU
    try these values for MTU

    the largest one that successfully pings is your MTU. You dont have to change any system settings to do this.

    Once you find out what it is, depending on your OS, you can change the appropriate settings.

    Always backup current settings before you change them just in case you break something.
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