PC will not connect to the internet all of a sudden

martinlest said:

Thanks for the replies..

Firstly, I am in a rented apartment in the middle of Bangkok. The apartment comes with a router but I don't have access to any of the setup details. I did disconnect the router, wait and then reconnect - but no change there. If there were a problem with the router itself, surely I would also get a problem with the Dell laptop (which has a wifi card). I can access the internet normally via the apartment's wifi on the Dell. The PC, as I say, had no WiFi card so I bought the D-Link USB device. It was working fine until yesterday. Then, if you see the other thread..

Boot times - how best to analyse?

.. my Adobe Flash crashed, and with it my internet access. I reinstalled the Adobe afresh - but the internet connection has gone..

I uninstalled the D-Link software and reinstalled it - there is only an option to install the drivers on the setup menu. This installs all the D-Link software. If I don't install this (my only other option) the D-Link stick does not flash orange, which is the indication that it is working.I don't have a cable anywhere near long enough to connect the PC to the router via the LAN port.

I could try pinging the DSL modem but how do I find the IP address?
The Dell and the PC are not linked together, on a network.

My LAN settings in IE are already set to automatically detect...

If the problem had been in the registry, wouldn't my having done a system restore to a time all was OK have fixed the problem (it didn't of course)?

There are a number of areas in which I consider myself 'expert' when it comes to PCs, but WiFi is definitely not one of them (so help much appreciated!).

Thanks again,

Martin

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I have seen WiFi adapters become defective. You should see if you can have your adapter tested, or try another one to verify it.

I have never seen a program like Adobe or others like it cause such an issue with the networking of a system.

A very good test to verify the computer's setup for networking would be to try a direct connection to a known working router port that has access to the internet.

If you have a cell phone that can be tethered, an interesting test would be to see if you can log on to the net using your cell phone and cell data service as a modem connection. The cell phone would normally be connected through the USB port, and thus would be making a similar type connection as that of a USB WiFi adapter. This would be an excellent test to verify the computer and its networking capability.

As for using a simple restore point process, care has to be taken that the restore point was not updated with a previous error.

The best process is to keep making full image backups of the system. I keep four full previous images of each of the systems I maintain. This way, if I have a complicated fault, I can easily take back an older image. After that I can easily make the necessary updates. Before restoring any full image, I make sure I backup the user files separately.

Investing in a number of large USB external drives is a very cheap solution in comparison to the loss of time and cost for restoring a system from zero.

At the system command prompt in the command window, if you type ipconfig /all you should see the IP of the DSL modem. It should be seen on the line called DNS Servers. In most of the systems I work on the IP for the DSL modem is 10.0.0.2

Also, look at the line DHCP server. You should see the IP of the router. Typically this could be 192.168.1.1 You can then ping the addresses shown to see if you get a return. An example is: ping 192.168.1.1

You can also do a loop back test by using: ping 127.0.0.1 This tests the actual NIC ports to see if they and the system are responding. This is a standard NIC loop back test.

Beyond this, you may require direct assistance from someone who is knowledgeable in networking, or simply re-install the OS, and including all the necessary drivers. Then rebuild the system from zero, and then copy back your user files. This would probably be your cheapest solution. If everything is done properly and there are no hardware faults, your system should work as normal.


:)

Try this, it is simple, and has worked in the past. Unplug the pc, and hold the power button for 30 seconds. Now leave the PC unplugged for 30 minutes. Plug it back in and boot up and see if you can get connected. this sounds too simplistic, but I have had it work for me personally, as well as having it work for others. It is certainly worth the attempt, and if, like me, it works, it's a "well I'll be damned" moment. A Guy

This section below is not right. Your computer is not able to see any DNS server! Maybe in your location the router is encorpated with the modem. I did not see any line indicating DHCP Server. I highlighted the errors in RED See your list below in the [QUOTE] where this error is indicated.

In the area where I believe your WiFi adapter is, it does not appear to have a proper or legitimate MAC address indicated. I highlighted these in BLUE.

What is also interesting, is in your list I don't see any default gateway. This normally should be the base address of the router, or the DSL router/modem device.


In Win7 you should see the network connection setup access in the path listed below.
Control Panel\Network and Internet\Network Connections

If you double click on your active network connection icon, you should be able to access its setup in detail. There are a number of levels of properties and setups involved. You can look through this for curiosity. You really have to know what you are doing and you will require the detailed information about your network to go through the setup and make changes manually, and apply the appropriate parameters. The complexity of this area in detail would be too deep to go in to over emails.


If I understand correctly, you tried a direct connection and it still did not work. This points to a problem with the drivers or setup of the NIC card. I have a strong feeling it is not defective.

Do the same list with the laptop that works and compare. This would be the best test to see the differences.

From the listing below, I can see that you will not have internet access. It looks like the networking of the computer cannot properly see the router and the DNS server.

If in the case where you would like to check the OS of your system, log in as administrator. You must run the command window as system administrator. If you have default admin rights, you can right keyclick on the CMD Processor icon, and select, Run as Administrator.

At the command prompt, type SFC/ SCANNOW Windows may display a warning, if you have the security set to high. Just click on OK to allow.

The Windows OS will make a system scan and correct any of the OS files that it finds to be defective. It will prompt you as it finds any that must be corrected, you have to be present to approve any of the corrections it finds.

You may need the Windows OS installation disk in the DVD/CD drive to use as a reference for the SFC program. If required the system will prompt you to insert the disk.

With some systems, you may have to create a super administrator account to run SFC. Read this site to have instructions about creating a super administrator account for Win7 or Vista: Built-in Administrator Account - Enable or Disable

Another thing you can try is to go to Device Manager. Open Network Adapters. Right click on the network adapter. Select Uninstall, and approve it. Then re-start the computer. It should automatically re-install itself on the re-start.

If it does not re-install you will require the drivers for it. Before uninstalling it, take note of its name and type. If you require a driver for it, use the other working computer and see if you can visit the manufacture site and download the driver.

If the network adapter (NIC) instals back and the error is the same, you can try to see if you can get a new copy of the drivers for the adapter. Maybe the original driver is corrupted.

I have a feeling that SFC /SCANNOW has a good chance to fix this problem. I also feel at this point that re-installing a new copy of the driver has even a better chance. Then the strongest chance which I am most sure about is to re-install the OS with the original installation disks and drivers for your computer.

I have my doubts the NIC part of your computer is defective! To me this is a driver, and or an OS issue.


:)

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martinlest said:

Thanks a lot for taking the trouble to reply in detail.

Before I look closely at the information you give, I have a bit more information. I got an extension LAN cable and linked the PC's LAN port to the router with it. Then, when I still couldn't get online I used the IE diagnostic. Windows Network Diagnostics says that "Local Area Connection does not have a valid IP configuration."

Meanwhile, when I plug the WiFi back in, the Dell laptop connects immediately. I guess there is a problem with the PC software rather than the hardware?? At the moment the PC is set to find the IP address automatically: I could add manual settings: I will try the settings you suggest - and those I got from my ping, but as I say, I am no expert in this, so do appreciate your time and help...

Will post back when I have had time to troubleshoot further.

Martin

LATER: Not really getting very far. My IPConfig /all gave this:

Microsoft Windows [Version 6.1.7600]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\Martin>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : Martin-PC
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : D-Link DWA-140 RangeBooster N USB Adapter
(rev.B2)
Physical Address. . . . . . . . . : 84-C9-B2-6F-50-56
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::e19a:1297:d4d5:cbae%14(Preferred)
Autoconfiguration IPv4 Address. . : 169.254.203.174(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCPv6 IAID . . . . . . . . . . . : 344246706
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-14-9E-3F-57-BC-AE-C5-02-8E-85

DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Local Area Connection:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Marvell Yukon 88E8056 PCI-E Gigabit Ether
net Controller
Physical Address. . . . . . . . . : BC-AE-C5-02-8E-85
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.{5182FF81-02DF-487F-853A-5B40FEABBEA3}:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Teredo Tunneling Pseudo-Interface:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.{B19237B8-2A3E-4614-990A-CE54973A1302}:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

C:\Users\Martin>