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we just replaced our Netgear switch due to failure. The original and replacement were the exact same model: GS752TXS-100NAS with 48 gigabit ports.
However, after the replacement was installed, one Windows XP machine on the network failed to connect to the switch. The Ethernet port did not light up and the computer reported Network Cable Disconnected.
I tested the cable, tried a different port on the switch, brought the computer into the same room with the switch and connected with a 3-foot cable, rebooted, etc. with no luck.
However, when I changed the computer's network card setting from Auto Negotiate to 100 Full, the connection instantly started working again.
The setting had always been on Auto before, and always worked fine. We have 30+ computers on this switch with different operating systems, network cards, etc. and have never had this problem before. Also this computer has never experienced this problem before.
Note also that after the original switch failed, we swapped in our old 100Mbit Cisco switch until the replacement arrived. This PC worked fine while connected to this Cisco switch also.
Does anyone have any idea why this happened, and what can be done about it to restore the computer's ability to auto-negotiate?
Thank you!
Ryan Griggs
Posted 2015-09-17T13:44:37.277
Reputation: 682
1The NIC drivers might be corrupt. Have you tried reinstalling them? Or is it possible the card might be going bad? – CharlieRB – 2015-09-17T15:03:46.493
We had some sort of voltage transient which hit our network and damaged several network cards etc, as well as our main switch. But when we replaced the damaged switch with our old Cisco switch, this computer connected just fine with no problems. It was only upon replacing with a new Netgear switch that the computer began showing Disconnected Cable message. – Ryan Griggs – 2015-09-17T15:43:28.027
I suppose there could have been some sort of damage to the card in the process, but why would it resume working after setting the speed manually? – Ryan Griggs – 2015-09-17T15:44:01.097
Unless setting the speed manually forced a reset of the card. Since this is a laptop, it was never fully powered off (did not pull the battery). So maybe the card just needed to be reset, and it may now work on the auto setting... I haven't tried this yet. – Ryan Griggs – 2015-09-17T15:44:49.417
Now that we know there was transient voltage that damaged network components, it adds a whole new dynamic to your question. At this point, anything is possible. Electronic damage from voltage spikes can do some really weird things. It could have damaged only part of the circuitry associated with the card, the whole card or even the motherboard. – CharlieRB – 2015-09-17T15:49:24.463
Yep, that's why I didn't mention it originally, as I knew "anything is possible" and "no way to explain" would be the go-to answers. However, since it works fine with auto-negotiate turned OFF, it doesn't seem to be an issue with the NIC or MB. I'm trying to determine what could cause auto-negotiate to fail if the physical layer is OK, which it obviously is in this case. – Ryan Griggs – 2015-09-17T19:30:04.057