Computer doesn't recognise ethernet cable

Tim_61 · Apr 20, 2016

Hi,

First of all, I will donate my last shirt to this site if anyone is able to help me with my problem!

I've now been trying to fix my computer for over a week, reading dozens of forum posts on the issue, replacing things, but all with now luck

So here is my problem, (I'm running Windows 7) around 10 days ago when I switched on my computer I noticed that I didn't have an internet connection, after inspecting the router I noticed that it was simply dead (everything else was fine, there wasn't a power surge, lightning etc.). After replacing the router I noticed that my onboard network controller (Marvell Yukon 88E8056 PCI-E Gigabit Ethernet Controller) wouldn't recognise any ethernet cable plugged into it. There is two ports and both of them are showing up in the device manager and network settings as working fine. I also went into my PC's Bios to confirm that both ports are enabled.

I have tried numerous fixes, like updating the driver/firmware, uninstalling/re-installing drivers, disable/enable. All without success.

Where it gets really odd, last weekend I decided to purchase a new network card, assuming that the ports might be faulty, however the exact same problem still exists.

Now one strange note, sometimes when switching on the computer the router will briefly have the port led, into which the ethernet cable is plugged into, flash up, and at the same time it will show in the Network Connections as connected on the Local Area Connection. This will only last for about a second and then keeps repeating.

Any help will be highly appreciated!

Joe Porter · Apr 20, 2016

It looks like you have tried a lot of the solutions I would have suggested. One of the last basic solutions which I imagine you have tried but not listed in your post is to try a different Ethernet cable. I guess you have already done that but thought I would suggest it in case!!!

techgeek · Apr 20, 2016

Some motherboards have a built in network cable checker in the BIOS, if yours does, go into the BIOS and check it's status there.

What motherboard do you have?

Tim_61 · Apr 20, 2016

Joe Porter :

Hi Joe, yup. I have tried a total of 5 cables. All virtually brand new and working on other systems.

Tim_61 · Apr 20, 2016

techgeek :

Yes, I believe I've seen that in the BIOS. Will try again now. My motherboard is an Asus P6X58D

Joe Porter · Apr 20, 2016

Try disabling the LAN in the BIOS and then install the new NIC you bought. The new NIC might not work whilst the on board LAN port is enabled.

techgeek · Apr 20, 2016

Had a look at your motherboard's manual, it's under Tools > Ai Net 2. It will check the cable at POST and put the results in that window. So enable it, restart the system and then go back into it, it should show the results.

Tim_61 · Apr 20, 2016

Joe Porter :

Already tried that. Unfortunately...

Tim_61 · Apr 20, 2016

techgeek :

OK that's interesting. So I just tried that and the response was: "Marvell LAN Cable not ready, enter setup for detail."

Does this mean it's definitely the cable? I honestly get the same issue with 5 different cables that are otherwise working. Also, how exactly do I get to see more details on this?

techgeek · Apr 20, 2016

Or the NIC's bad. Did you try both this way?

techgeek · Apr 20, 2016

Actually I think I misunderstood how that AI Net 2 works. It should show the status of any connected cable for any onboard NIC that's enabled. You don't have to enable it to check at POST to see it in the BIOS. That only stops the POST with a warning that it wasn't ready. I guess this would be a useful feature for LAN booting.

Funny thing is my wifes old C2Q system has this same feature and I can see each pair listed and the estimated length of each pair (10 - 11 meters). However my newer Haswell system doesn't have this feature, I can't see anything regarding my LAN cable.

Tim_61 · Apr 20, 2016

techgeek :

Sorry, I actually tried out that function on my new NIC, which obviously couldn't work. I have now tried this with both of the onboard NIC's and both recognise the cable just fine. Showing at pair 4-5 and 7-8 with status "short" and length 1.6m.

Does this help in any way? Possibly at least excludes the possibility of a bad cable?

techgeek · Apr 20, 2016

It means the NIC's are "functional" and seems more like an OS issue than a hardware issue. And yes it most definitely eliminates a bad cable as the problem.

You said it doesn't work in Windows 7 and Server 2012? This would seem weird as you wouldn't expect both to exhibit the same issue.

Just for shits and giggles, you wouldn't have a live CD of Linux would you? You could see if they work there. Have you tried Safe Mode with networking?

I should have asked this in the beginning, do the ports on your router have LED's on them and if so, do they light when your NIC is plugged into them?

Tim_61 · Apr 20, 2016

techgeek :

I'm only running Windows 7, not sure about Server 2012?

No Linux unfortunately. Will try the Safe Mode with networking right now.

Yes, the ports on my routher have LED's. They are now doing the thing again I had described in my original post:

...the router will briefly have the port led, into which the ethernet cable is plugged into, flash up, and at the same time it will show in the Network Connections as connected on the Local Area Connection. This will only last for about a second and then keeps repeating.

Thanks so much for your help so far btw!!

techgeek · Apr 20, 2016

Oh sorry, I must have gotten confused with another thread I'm working in with regards to Windows Server 2012.

I'm thinking something might be messed up with Windows networking stack. Not 100% sure though. It would explain why a brand new add in NIC isn't working either.

Hopefully Safe Mode with Networking will show us something.

As for the odd LED behaviour, it almost seem something is interrupting the initial negotiation with the DHCP server in your router most likely on the PC's side. Though you could try connecting your NIC directly to your modem and see if it's able to negotiate a connection to your ISP.

If you get through all this, I might get you to run this from an elevated command prompt:

sfc /scannow

This will check the Windows system files and hopefully repair / replace any that are corrupted or missing.

Tim_61 · Apr 20, 2016

techgeek :

Ok, so it was basically exactly the same in safe mode. In the Network Connections it cycles through "Identifying...", briefly "Enabled" for around 2-3 seconds and then again "Network cable unplugged" and repeats this, all while the LED on the router for that port is flashing.

The router also has the ADSL LED flashing up every now and then for a while.

Trying the sfc scan as we speak.

techgeek · Apr 20, 2016

Did you try to connect the onboard NIC directly to your modem? Just in case this is an issue with the new router.

Tim_61 · Apr 20, 2016

techgeek :

oh, I think that got me confused a bit. I've got a Huawei HG532D. I believe that is modem and router at the same time? :??:

Tim_61 · Apr 20, 2016

The scan was just completed and turned out with: "Windows Resorce Protection did not find any integrity violations."

techgeek · Apr 20, 2016

OK, well it looks like Windows is OK. Which doesn't necessarily mean that it still couldn't be a problem with Windows, it's just not a problem with corrupt or missing files.

So your router is a router / modem combo, so there is no way to isolate the router from the equation. My ISP uses this combo too, which ticks me off to no end.

My gut is telling me this is a problem with Windows because your new NIC doesn't work either. That or it's your new router / modem. Do you have any other computers connected to this router / modem via ethernet that do get an internet connection?

Tim_61 · Apr 20, 2016

techgeek :

This is the only computer connected. Unfortunately I don't have another one handy to try. I should also add that the router is from my girlfriend who bought this a year or so ago for her apartment and then ended up using another one. So it's basically like new and has been working previously.

I agree with your gut feeling that it's gotta be some problem with Windows. Any other tests I could run?

I just remembered that the whole thing also started after windows had installed an update. I believe it was on April 11th. I had already tried system recovery from that point, but that was for some reason unsuccesful and now that recovery point is gone.

Joe Porter · Apr 20, 2016

Can you go on programs and features, view installed updates and uninstall the updates on that date from there. If that solves it you can then install the updates one by one to see which one caused the issue.

techgeek · Apr 20, 2016

I don't want to send you down the road of a Windows re-install like some shady OEM support would have you do just to get you off the phone. I'm just worried that we could waste a lot of time fighting something that might be a re-install away to fix.

Give this a try from a elevated command prompt:

netsh int ip reset c:\resettcpip.txt

Restart the computer after this command finishes.

Tim_61 · Apr 20, 2016

techgeek :

I feel like I had seen and tried this from one of the dozens of threads I've read before, but will give it a go

Tim_61 · Apr 20, 2016

No luck...this is really doing my head in!

Computer doesn't recognise ethernet cable

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