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unable to contact your DHCP server problem

Discussion in 'Networking' started by chilakilez, Jan 11, 2010.

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  1. chilakilez

    chilakilez Thread Starter

    Nov 27, 2009
    Hi there,
    i've been having this annoying issue with my wireless connection, every now and then it gets disconnected and stays under "Limited Connectivity", i try to reset the IP and get the "unable to contact your DHCP server" problem, and i cannot do any of the ipconfig tasks due to the same error. The main problem is that i cannot have internet again until i restart the laptop, and even if i turn it off and back again, then it says "Windows Cannot find any Networks", or "try switching your wireless mode on", even though it's on and there are about 8 differenet wireless connections in here.
    I know it's my laptop but is the wireless card damaged or something?.

    I have a Toshiba Satellite A100 / SP3
    with a
    Intel(R) PRO/Wireless 3945ABG Network Connection
    and im connected wireless to a WEP.
    Drivers are updated and no configurations problems appear under device manager.
    Thanks in advance for any help.
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  3. pccare_himanshu


    Nov 3, 2009
    Some steps which i Know

    STEP 1:

    Do a power cycle ( Shutdown the computer, unplug the cable from the cable or the
    DSL modem from the back of the tower and also unplug the cable from the DSL or
    cable modem and power off the cable or the DSL modem and restablish the setup after
    2 minutes and power on ) .

    STEP 2:
    Check the Network Properties for any Network Bridge

    How to remove the Network bridge :
    1. Click on Start and go to the Control Panel (start-->settings-->control panel if
    they have it set to windows classic)

    2. Click on Network and Internet Connections (network connections if they have
    already switched away from category view)

    3. Click on Network Connections (you will not use this step if they have already
    switched away from category view)

    4. Look out for the things available ( Ask the customer to read the names that are
    present )

    5. If they have a network bridge, right click on it and choose delete.

    More often then not, if they had a network bridge, this will solve the DHCP server
    error problem

    STEP 3:
    You can try resetting TCP/IP with the netsh command or try the netsh dump (commonly
    called by me the netBS commands)

    Reset TCP/IP in Windows XP

    1. Click on Start and go to Run

    2. In the run box type "cmd" or "command"

    3. At the command prompt type in "netsh int ip reset reset.txt" and hit enter

    You'll see the cursor go down a line for a second or two and then it will go back
    to the command prompt.

    How to do do netsh dump:
    Netsh dump

    This is another IP fix at that I consider sub-par. It sure doesn't fix the reg keys
    and that's what matters some times.

    1. click on start and go to run

    2. type in the run box "cmd" or "command" and click OK

    3. At the command prompt type in "netsh dump" and hit enter

    A bunch of stuff is going to flash across the screen and you will end up back at
    the command prompt.

    4. Exit out of the command prompt and reboot.

    STEP 4:
    Another option would be trying to reinstall the NIC or possibly changing the link
    speed, however it is seldom that either of these work.

    Reinstalling the NIC :
    1. Go to the Device Manager

    2. click on the plus sign to the left of Network Adapters

    3. Highlight the NIC and hit delete on the keyboard. It will ask you if you're sure
    you want to uninstall it. Click on yes.

    4. Reboot

    When the system reboots, in the system tray you will see a little bubble window pop
    up saying new hardware found. A little later it should say that the new hardware
    was installed and ready to use.

    Changing the link speed of the NIC :

    1. Open up the Device Manager

    2. Find the NIC underneath Network Adapters

    3. Double click on it

    4. Click on the Advanced Tab

    5. In the properties list highlight Media Type and change the value on the left to
    10mbps Half Duplex or 10 half.

    STEP 5:
    If the computer is connected to the internet by means of a wireless netadaptor, we
    can try connecting the computer to the router or the modem by means of a wire. If
    the computer connects to the internet by means of the wired connection, then we can
    understand that the problem is with the configuration of the wireless adaptor (
    Sometimes the wireless netadaptor may have a problem ).

    STEP 6:
    Put the computer on a partial clean boot and check whether any 3party service is
    causing the problem. Uninstall any 3rdparty firewall ( If present ).

    STEP 7:

    1) Start >> run >> services.msc >> open" DHCP client " >>go to "Dependencies" and
    check for the following items.

    AFD Networking Support environment
    Net BIOS over TCP/IP
    TCP/IP Protocol Driver

    If you have anything other than this, DHCP has been modified by some unidentified
    source. ( Make sure that the DHCP client is set to automatic and if it is stopped
    make it restart the service ).

    2) Navigate to HKey_Local_Machine\System\CurrentControlSet\Services\DHCP and edit
    the "DependOnService" on the right side.

    3) Also Navigate to HKey_Local_Machine\System\CurrentControlSet\Services and delete
    winsock and winsock 2.

    4) Restart the computer.

    5) Reinstall TCP/IP.

    How to reinstall TCP/IP
    Install TCP/IP :
    i ) Right-click the network connection, and then click Properties.

    ii )Click Internet protocol TCP/IP and click Install.

    iii )Click Protocol, and then click Add.

    iv )Click Have Disk.

    v )Type C:\Windows\inf , and then click OK.

    vi )On the list of available protocols, click Internet Protocol (TCP/IP), and then
    click OK.

    vii )Restart the computer.

    NOTE : If you are working with a SP2 installation please dont delete the winsock
    keys from the registry. Use "netsh winsock reset" ( without quotes ) in the command
    prompt to reset winsock.

    6) Now check the Ip address and also try to release and renew it. The error wont
    come 90%.

    STEP 8:
    We can also try to restore the system back to an earlier time ( when it was working
    fine ) by doing a system restore.

    The best option if none of those work would be to try USB if it is available. If
    the customer feels it is the modem then tell them they can swap the cable modem at
    the local office, but if they are still unableto receive an IP address they might
    want to consider taking their computer to the shop, or troubleshoot the system
    themselves. The reason I say this....we are not responsible for their system.

    STEP 9:

    If the computer is infected by a lot of spyware none of these steps will work (
    Sometimes the computer will connect to the internet after STEP 3, but it will fail
    to work after a couple of restarts. I have faced this kind of situation on one
    call). If this is the case we can do a clean install of
    windows Xp.
  4. chilakilez

    chilakilez Thread Starter

    Nov 27, 2009
    thanks a lot, will try them when it happens and will post back
  5. TerryNet

    TerryNet Terry Moderator

    Mar 23, 2005
    Most of those above steps are going to be a waste of your time, so pick and choose which ones seem relevant to your issue.

    When I see "Windows Cannot find any Networks", or "try switching your wireless mode on" the first thing I think of is that you are using an integrated wireless adapter and it is switched off. Have you checked for that when you get either of those messages?

    I understand that on Toshibas the switch is low on the front of the laptop, and the LED to indicate status is Red for on. There may also be a software switch (utility).
  6. chilakilez

    chilakilez Thread Starter

    Nov 27, 2009
    Whenever i turn the switch off, and turn it back on again, then it's when it appears "Windows Cannot find any Networks" if i don't turn it off it remains connected to the network under "Limited Connectivity".
    And indeed, there is a Toshiba utility, same results whenever i turn it off and on.
    Somehow there is something that works just restarting the laptop.
  7. TerryNet

    TerryNet Terry Moderator

    Mar 23, 2005
    What operating system?
  8. JohnWill

    JohnWill Retired Moderator

    Oct 19, 2002
    Download and run this Xirrus Wi-Fi Inspector, paste a screen shot of the main screen here.

    To post a screen shot of the active window, hold the Alt key and press the PrtScn key. Open the Windows PAINT application and Paste the screen shot. You can then use PAINT to trim to suit, and save it as a JPG format file. To upload it to the forum, open the full reply window and use the Manage Attachments button to upload it here.
  9. chilakilez

    chilakilez Thread Starter

    Nov 27, 2009
    it's Windows Vista Home Premium / SP2 and will do post the screenshot asap, thanks guys
  10. TerryNet

    TerryNet Terry Moderator

    Mar 23, 2005
    You have the latest wireless driver from Toshiba's web site, right? Intel warns that sometimes the motherboard or PC manufacturer makes changes to their drivers to make them work in the particular system.
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