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I noticed a weird problem today on my laptop. Apparently, it only connects on the Ethernet cable located on to my desk but not in any other port in my office. When I tried to get connected using a land cable of a different desk, the networking icon on the status bar showed an exclamation mark and refused to connect. Though this is a large company I am working at, they have not applied any restriction policy "laptop per Ethernet plug", so it must be something software or hardware specific. I have tried to release and renew my IP address, reinstalled from scratch the network drivers and contacted the IT help desk; no fix so far.

Is there any possibility that my network card starts degrading or is in a bad state? The laptop is only 6 months old. I have tried with multiple land cables and different plugs, it connects to my desk only.

PS: Laptop successfully connects to the open WiFi of my company and to networks outside the intranet.

Lefteris008
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2 Answers2

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That exclamation mark means there is a problem with DNS. Windows tries to resolve some known DNS names and then if it fails tells you that there is no Internet access.

More than likely, there is some config or setting applied to the network and the people you've talked to just don't know about it. You will need to do a lot of things to troubleshoot this:

  1. See if the LEDs on your NIC light up. if they don't, there is nothing on the other side of the cable.
  2. Make sure the adapter is enabled in the Network and Sharing center
  3. Try a different cable.
  4. Test the cable to make sure it's TIA-568B.
  5. Try a different switch port.
  6. Try a different switch in the rack.
  7. Try a different PC/device on that port in the wall.
  8. Tell us what the IP settings for that NIC are (static, DHCP, IP address, etc).
  9. If you have a 169.254.x.x address, then that means DHCP is failing.
  10. If DHCP is working, find out if the DNS servers being handed out on the problematic port are the ones you are supposed to get.
  11. Ping the gateway and DNS servers. They should respond.
  12. Change your DNS servers on your NIC to something public with a high uptime like Google, OpenDNS, or whatever you prefer.
  13. As a last resort, you could get your IT people to come to your office/site to fix it.
YetAnotherRandomUser
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Here is my answer and a comment to Dan Whaley, because I can't comment directly.

@Lefteris008, indeed what Dan says is true. It will be difficult to answer your question with 100% certainty without having access to the equipment.

But I think I can provide a good approach nevertheless. There are 3 possibilities, 2 more probable and a 3rd way less likely.

1) Most probable:

The other unused ports are not connected in the switch. This is quite common to save on switch ports and cabling. You may test if this is the case by unplugging another guy's computer and pluggin yours.

2) Second most probable, possible the answer if the previous experiment failed:

I wouldn't discard the fact that your MAC address has been restricted to connect to only one port in the switch. This is done in the switch configuration and is quite common in big corporations. Reasons to suspect this:

  • You get a connection in your seat, this means that everything works properly when you're in your seat.
  • You don't even get the most basic network connectivity when you try the other connectors, as no leds light up (Behavior that you get if there is no cable or the switch port is blocked).

3) The third possibility: Your card degraded as you say and you're in a port that has a better SNR than the others, but this seems a very very big coincidence and although possible, it is unlikely.

@Dan Whaley: Network cards DO degrade as all electronics do. At the lower level, you always work with an analogic Signal-to-Noise ratio(SNR), as the real world is not digital.

I've seen computers failing to connect to a certain network due to the use of a longer cable (which would cause a lower SNR). That same cable would be good for a different card.

Telegrapher
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