Network cable disconnects itself ?!

daveza

daveza

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Love this job, always something new.

So I'm working on a pc that has a problem connecting to the internet.

I've had the same machine a few times before riddled with viruses - easy money to clean them and wait a few months before doing it all over again ( they don't learn ).

So this time I do the usual, odd trojan here and there all cleaned, access to the internet is fine, then -

out of the blue the taskbar shows network cable disconnected. No internet access. Cable is definitely connected.

All settings on the network adaptor are standard.

I've never seen this happen before - any ideas ?
 
Does the icon have a red X or yellow ! mark?
What AV do you use.
Is the router in proper working order?
Is the network cable in working order?
 
Last edited:
daveza said:
Love this job, always something new.

So I'm working on a pc that has a problem connecting to the internet.

I've had the same machine a few times before riddled with viruses - easy money to clean them and wait a few months before doing it all over again ( they don't learn ).

So this time I do the usual, odd trojan here and there all cleaned, access to the internet is fine, then -

out of the blue the taskbar shows network cable disconnected. No internet access. Cable is definitely connected.

All settings on the network adaptor are standard.

I've never seen this happen before - any ideas ?
Click to expand...

PCI network card?

Anyway, first try uninstalling the device in device manager and restart. If it still doesn't work... do above!
 
Red X

Onboard network card.

I do 95% remote support, so yes, router, switch, firewall, everything else as it should be.

I have just never seen a network port go offline out of the blue - one minute the two blue pc's are there, next minute red cross.

edit: oh, and device manager has no yellow ! and says the device is working.
 
Last edited:
daveza said:
Red X

Onboard network card.

I do 95% remote support, so yes, router, switch, firewall, everything else as it should be.

I have just never seen a network port go offline out of the blue - one minute the two blue pc's are there, next minute red cross.

edit: oh, and device manager has no yellow ! and says the device is working.
Click to expand...

I have, once or twice. Its rare.

Another option is to put other HDD in and just load a clean OS, to just eliminate OS as cause.
 
daveza said:
Red X

Onboard network card.

I do 95% remote support, so yes, router, switch, firewall, everything else as it should be.

I have just never seen a network port go offline out of the blue - one minute the two blue pc's are there, next minute red cross.

edit: oh, and device manager has no yellow ! and says the device is working.
Click to expand...

make sure the network point on the cable is clean..
I have seen what frying oil close to a PC can cause.

if persists and you have ruled out any router/switch errors, insert a LAN card. Oh and make sure the LAN driver is not corrupted.
 
Does it come back on? If so, what are the conditions of the return (restart etc.)

Can you reproduce the disconnection?

I'd try running in Safe Mode to rule out software intervention. Then try checking the cable, especially the connectors for disconnection from the little plug points in the RJ45.

Failing that, check drivers, then the card itself.
 
I'd try running in Safe Mode to rule out software intervention.
Click to expand...

What software intervention would cause that - I ask because this pc has been a rabbit warren of malware and viruses.

While I'm aware viruses can block internet access I have yet to see one causing a network disconnection.
 
daveza said:
What software intervention would cause that - I ask because this pc has been a rabbit warren of malware and viruses.

While I'm aware viruses can block internet access I have yet to see one causing a network disconnection.
Click to expand...

Format and clean install, who uses Win XP?!?!
 
After checking all the obvious things like cable, plug, switch, drivers, etc, etc ... try adding another physical NIC (eg USB). Switch betw the two, alternating disable/enable. If the new NIC is stable, start suspecting dry joints or poor connections on the mobo's NIC connectors and circuitry.
 
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