Unable to Connect to Internet

* Check for IP address using the command ipconfig from the command prompt.
* There are three possible types of IP addresses.

* Invalid IP address.
* Valid IP Address.
* 0.0.0.0

Workaround:

If IP address is invalid then the ip address will begin with 169.254.xxx.xxx.In this case follow these troubleshooting

Go to command prompt and run

Ipconfig /release
Ipconfig /renew

An error will definitely be returned

IF the error is Unable to contact DHCP server or Unable to locate host then try

Power Cycling the Modem.
Checking in safe mode with Networking.
Uninstall and reinstall the network Adapter.
Uninstall any security software present in the computer including the traces of remains of any uninstalled software.
Check whether the DNS and DHCP Services are started in the services.msc
Netsh Winsock Reset
Rebuild TCP/IP manually.

If any other error message is returned then try

Netsh Winsock Reset
Rebuild TCP/IP manually
Perform a flush DNS and register DNS
Uninstall any security software present in the computer including the traces of remains of any uninstalled software.

If the IP address is valid then try the following steps

Follow the ping test in the below mentioned order

Ping 127.0.0.1 and if it succeeds proceed to the next step. If the ping test fails then do the following

Uninstall and reinstall the network Adapter
Uninstall the security software present in the computer

Ping the IP Address of the computer and if it succeeds proceed to the next step. If the ping test fails then do the following

Uninstall the security software present in the computer
Reinstall the TCP/IP protocol
Uninstall any other third party software that might stop the connection

Ping the default gateway of the computer and if it succeeds proceed to the next step. If the ping test fails then do the following

Perform a power cycle
Uninstall and reinstall the network Adapter
Uninstall the security software present in the computer
Conference the call with ISP

Ping the FQDN (website) and if it succeeds proceed to the next step. If the ping test fails then do the following

Uninstall the security software present in the computer
Conference the call with ISP

Ping the IP address of the FQDN and if it succeeds proceed to the next step. If the ping test fails then do the following

Conference the call with ISP directly.
Perform a flush DNS
Force the global DNS 4.2.2.2

If all ping tests succeed then

Try in safe mode with networking.
Perform a clean boot if that succeeds.
Bypass Router if present.
Perform IE Optimization.
Uninstall the third party toolbars, search bars, popup blockers; Google desktop software, connection manager and web accelerators.
Create a new user account.
Perform an SFC /scannow

If all these steps fail perform a repair installation.

If IP address is 0.0.0.0 then perform the following

Uninstall and reinstall the network Adapter
Check whether the DNS and DHCP Services are started in the services.msc
Check for the dependencies in registry location HKLM\System\Currentcontrolset\Services\DHCP.
The depend on service value should be TCPIP, AFD, NetBt.

Unable to Browse the Internet

If connectivity is confirmed and the issue is only with browsing

System Restore
IE Optimization
No Addons Mode
IE Reset
Uninstall the third party toolbars, search bars, popup blockers; Google desktop software, connection manager and web accelerators
Checking for Traces of Corrupted Browser (IE8/IE7), If found Uninstalling it.
Safe mode with Networking

Re-register the following dll files

Urlmon.dll
Shdocvw.dll
Browseui.dll
Mshtml.dll
Mshtmled.dll
Wininet.dll
Hlink.dll
Asctrls.ocx
Dxtrans.dll
Dxtmsft.dll
Imgutil.dll
Scrrun.dll
Msxml.dll
Msjava.dll
Jscript.dll
Softpub.dll
Wintrust.dll
Initpki.dll
Dssenh.dll
Rsaenh.dll
Gpkcsp.dll
Sccbase.dll
Slbcsp.dll
Cryptdlg.dll

Disable/Uninstall Security Software
Perform a Virus Scan on the computer
Check with a New User account
Perform an SFC/Scannow

 

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