unable to contact your DHCP server problem

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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.
Nov 3, 2009
Some steps which i Know


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 ) .

Check the Network Properties for any Network Bridge

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

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

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.

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.

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
10mbps Half Duplex or 10 half.

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 ).

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


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.

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
to reset winsock.

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

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
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.


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


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).


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.


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.


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


Mar 23, 2005
Drivers are updated ...
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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