I have a server lab with an ASROCK motherboard. Built this server about 6 months ago.

Today, while working on it, the NIC Local Area Connection (Ethernet) suddenly showed that the cable is unplugged. After checking the cable and router, I went to device manager and the REALTEK device shows that it is working fine.

I've tested the cable, tried other working cables, nothing. I then went to REALTEK's website to download the updated driver and installed it. Still nothing.

I've never seen a malfunctioning NIC card that would only not recognize a cable is connected, yet will show up fine in Device Manager.

I happen to have an expansion PCIe Ethernet card that I will put in later this week, but I was wondering if any of you have run into this on a server setting before? I did not physically check the inside of the ethernet port yet, maybe one of the pins got loose or something for all I know.

Any suggestions our comments would be appreciated it. Thanks

  • Have you tried a different switch port? – joeqwerty Jan 2 '18 at 12:17
  • yes, and I tried my laptop on all ports of the router, successfully. – Zach85 Jan 3 '18 at 1:02

There are several possibilities for a link to fail:

  1. The cable is bad/damaged.
  2. The NIC died. It may still look OK from the system side.
  3. The switch port died. As with the NIC, the switch may not be aware that the port is malfunctioning.

Using known-good equipment you need to rule out one by the other - you've already done that with the cable.

  • I have tested 1 and 3 already with other cables and my laptop on all of the ports on the router. – Zach85 Jan 3 '18 at 0:47
  • I ended up doing a late-night hardware install with my PCIe network card last night and got my server lab back online. I'm going to try and do some other tests on my on-board NIC before calling it dead. Just not sure why it would show up still in device manager if it won't turn on with a network cable plugged in. – Zach85 Jan 3 '18 at 0:49
  • One last thing. I used a MAC changer to test something on that NIC with TMAC v6. Could that have done anything, maybe a lock on that port without the original MAC address? I tried changing it back to its original MAC address but still doesn't work – Zach85 Jan 3 '18 at 0:50
  • Changing the MAC address shouldn't have any impact on the link but I have no idea what that software did - usually you just enter the desired MAC address in the NIC's advanced settings. – Zac67 Jan 3 '18 at 10:07
  • So after several attempts to revive the on-board nic, it seems as if something inside the port had died, regardless of the whole network adapter is still showing up in Device Manager and Network properties. I'll be using my spare PCI network adapter for now, maybe later this summer I'll replace the motherboard. Thank you everyone for your assistance – Zach85 Jan 9 '18 at 22:20

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