cannot access internet through router

I have 4 PC's on my home network all connected to my router. (dlink)

one PC cannot connect to the internet when connected to the router.
but can when connected directly to the modem.

I *CAN access my routers admin panel from the PC when connected to the router. but the router shows the cable as unplugged. (strange)

The PC *DOES get a valid IP address from the router

I've tried different cables ect...

i verified that it is set to obtain an IP and DNS automatically there are no proxy settings in connections

strangely the ping command and the ipconfig do not work (I can't remember the exact error message but basically they do not exist)

 

Remove a working computer / cable from the router and plug in the problem computer into the same port on router. If it magically works, you may have a bad port on router. Connect one of the working computers into this suspect port, does it also fail?
Also, some routers provide a port which bypasses the router ... sometimes referred as DMZ. This is to allow a connection outside of router control. Never worked with such a router or if any configuration is required to have them function / connect to Internet.

 

thnx,

I've tried mis-matching ports and same results. DMZ is disabled.

 

With this statement it would appear their is communication via computer and router... maybe not complete. Could NIC be dying a slow death. Also check your firewall / rules.

This would support working NIC and cable. Are you ADDING a fourth computer to your network, or has this been a good working 4 computer network that started to have this problem?

 

Another suggestion ... with all four computers at desktop and attached to router. Power down modem and router, wait 5 minutes. Bring up modem, wait until all lights are active (except activity light), then power up router.

 

In this sort of situation, it is always worth going back to basics. "Cannot access Internet" covers a lot from problems with your browser configuration, to a faulty cable.

Start with the basics.

Can you ping the router's IP address (e.g. PING 192.168.1.1)? If so it's unlike to be cable, or basic connectivity problem

Can you ping your ISP's DNS server's IP address? If this works, nine time out of ten the problem is DNS name resolution. Try pinging a web site (e.g. PING www.google.com). If this fails your DNS isn't set up correctly. Check you DNS settings.

If you've got this far without errors, the problem isn't a "network" problem as such, but rather the configuration of your PC. First thing I'd suggest is that you check your connection setting in Internet Explorer. Select "Internet Options" from the Tools menu and then click on the Connections tab. For IE to work with a router, the option "Never dial a connection" needs to be set (or "Dial whenever a network connection is not present" if you occasionally use a modem). If "Always dial my default connection" is set, this would account for why you can connect with a modem and not through the router. I'm guessing this could well be your problem.

Also check your firewall settings.

 

i think you mis-understood, when I said I could connect through the modem, i meant cable modem, not dial up.

unfortunately the "ping" command does not work but I can access the routers control panel, however the router shows the cable as unplugged. (multiple cables tested)

I have also verified the TCP/IP settings, and it is setup to obtain IP and DNS automatically which it does.

I have verified the browser connections, note this problem is not restricted to web browsing, there is simply no network access.

firewall is setup to allow internet access to any device connected and block any incoming connections (typical configuration). anything plugged in with this exception, works fine.


I'm going to assume based on the technical info here that the most probable cause is a bad NIC card.

 

this is a new PC I am adding

 

If the cable modem is connected to the computer via a USB connector, the system can see it as a dial-up device even if it is not.

and

That suggests that the problem is with TCP/IP on your PC. PING and IPCONFIG are some of the applications contained in the package you install when you install TCP/IP. They should work no matter what you have connected to the PC. You need to strip off TCP/IP and reinstall it.

It's possible there is a NIC fault too, but you need to sort out the TCP/IP problem first.