changing the speed of my network connections from auto to 100mb/full duplex

Posted on 2004-11-04
Last Modified: 2010-04-12
I need to edit the registry to change the speed of my network connections from auto to 100mb/full duplex on a windows 2000 computer. I did it for XP but for W2K is different.

Question by:voegueda71
    LVL 11

    Expert Comment

    Hello voegueda71,

    What kind of network card is it ? Most NIC manufactures would have utilities you can download from their website that would do this for you.


    Author Comment

    Well It will be done to multiple computers,  laptops and desktops.  Its really handy to just one key(modified reg key) actually 2 one that will set it to full duplex and other that will set it to auto.
    I currently have one for XP computers and it's working fine.
    The idea for this is when users take laptops on the road they need to change Network speed to auto and back to full duplex  when they use it  at work.
    LVL 11

    Accepted Solution

    Hello Voegueda

    Even if you were to attempt changing it with a registry key, the registry key would be different for the various different NICs installed on your different computers.

    If you are really inclined to do it using the registry, then you can use a free registry tool called Regmon from Sysinternals (available at ). Then you would have to go to "each unique" machine, that uses the same NIC and try and change the NIC settings while you are running the Regmon tool. This would tell you the exact locations and and keys that change. You would have to make a careful note of that, export them and save it in a .reg file. You would have to do this step for each brand of the NIC on your network. Once you have determined that, its simply a matter of automating the .reg file being run from a batch file. Thats the best I can think of, it would still save you time if you did not have several differnt brands of Network cards on your network.

    Another thing, do you have a Switch or a Router on your LAN ? If you do, then with certain switches and routers, its possible to set the port speeds on the the router / switch itself (using VLAN etc). This might be something you want to look at too.

    Good Luck!

    Author Comment

    I figure out:
    The key is located at:

    There are a series of sub-keys, such as 0000, 0001, 0002 etc.
    One of them is the key for the network adaptor.
    For Windows 2000: SubKey is 0000
    in the righthand pane, you'll see DuplexMode and Media Select.  

    First  Manually Configure  Ethernet Controller to one setting ( sample: 100/full duplex  )
    To do this Go to:
    Network Places: right click and select Properties,  
    On network connections window: select Local area    
    Local area Connections Properties:
     Click configure ->Advance tab->Under Property You will see DuplexMode and Media type
    Change the setting to what you want:

    Then Crate a REG file.
    Make sure the proper 000x number is highlighted and export the
    key (File menu) .  It will create a REG file.  This can be merged back into the registry by doubleclicking it.
    Do the same thing with the second setting.

    Author Comment

    I didn't use Regmon to do this, but thanks to your suggestions I was able to notice the changes in the registry and that made easier to do what I wanted to do.

    Thank you.

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