Basic trouble shooting steps for your internet connectivity issues:

1) Make sure there is no back-ground programs such as P2P networks running.
2) Clear your cache and cookies. If you have too much store on your computer you can lose all connectivity.
3) Go to start menu > programs > accessories > system tools > Disk Clean Up. This will delete temporary files and store internet pages (similar to clear cache but more manual, especially if you use multiple browsers)
4) Flush your DNS. Start menu > RUN > type CMD > Hit enter. On the command prompt type ipconfing /flushdns Sometimes too many name services can be stored and cause too large of a lookup table.
5) Renew your IP address. Start menu > run > type CMD > Hit enter. On the command prompt type ipconfing / release then type ipconfig / renew This should pull a new ip address from your DHCP.
6) Disconnect your modem and router. Remove the thick black cable (coaxial cable) from the modem. Remove all physical wires from the router. Turn off both devices for 30 seconds. Shut down all computers on the network. Then reconnect all devices and cables then turn on every computer.
7) Try to directly connect your modem to the network interface card (do not use your router). This will help determine if your modem is bad, router is bad or other issues.


If your connectivity issues persist try to use net analyzer utilities built into windows.

Go to start menu > run > type CMD > hit enter

On the command prompt type: ping 127.0.0.1 then hit ENTER
This command will ping your NETWORK INTERFACE CARD (NIC). This will help you determine if it is a local problem or an outside problem.

Next, ping your router, the router ip address differs from manufacturer to manufacturer.
To find the router Ip address type: ipconfig and hit ENTER

Your window will display something like;
IP Address - 172.16.0.1
Subnetmask - 255.255.255.0
Default Gateway - 172.16.0.1

Next type the command (in this case using my example)
ping 172.16.0.1 This will "hit" the router to see if it is receiving and send packets.

Next step, trying to ping outside address.
try to ping well known addresses
ping www.google.com
ping www.yahoo.com
ping www.msn.com

The next to try is using your netstat tools.
Open a web browser then go to your command prompt
type the command

netstat -n Hit the ENTER key.
You can see all of the active and listening connections. If there are connections Established but you are unable to view the webpages it means you're sending Data but you are not RECEIVING data. If you have no connections establish you need to call your ISP.

If the packets fail you likely have an outtage of some sort and call your ISP. If the packets are not dropped you may then start considering other things such as virus' or bandwidth issues or lastly physical wiring issues from the ISP to your house.



Thanks to przy for making this guide.

This post was edited by Serria on May 3 2009 01:31pm