Can ethernet cables go bad on their own?

[FranzJoseph]

Yesterday, my UTP CAT6 cable just suddenly died. No LED flicker at the router, no signal, yet the router was routing everything else just fine. First I thought it might be a port misconfiguration, but no.

The cable has been in place for a few years, with exactly zero active tugs or twists on it, the whole run was fixed in place and neither the computer or the router were ever moved an inch, AFAIK. No storms or lightning here either, plus the run is too short for any transients and both the box and router are on mains surge protectors.

Maybe some slow creeping elastic deformation of some kinked wire finally reached its limit of elasticity and broke? Maybe heat from the fan exhaust directly in front of the cable added to it? Or maybe just lightly touching the cable while plugging in a USB device nearby did break a wire at its limit? Catching at straws here.

I am perplexed. I've yet to bring out the multimeter to test it. Weird...

 

[steelghost]

If you try another cable between the same two ports, does it work again?

I'd have bet on a dead port in a router or switch before I expected a cable to "just die"...

 

[FranzJoseph]

If you try another cable between the same two ports, does it work again?

I'd have bet on a dead port in a router or switch before I expected a cable to "just die"...

That's the second thing I did (after re‑seating the old cable a few times and checking comp and router configs through wifi). And yes, the new cable just works in the same ports.

 

[tb12939]

That's the second thing I did (after re‑seating the old cable a few times and checking comp and router configs through wifi). And yes, the new cable just works in the same ports.

I'd suspect oxidation but normally reconnecting it a few times would be enough cleaning by friction to bring it back to life

 

[steelghost]

Seems like multimeter time!

 

[FranzJoseph]

I'd suspect oxidation but normally reconnecting it a few times would be enough cleaning by friction to bring it back to life

Looks like either oxidation, gunk delivered from the fan exhaust (that computer was in the kitchen where PM is probably much higher even with ventilation) or even both. A thorough cleaning did make it work at last, but since there could still be a pinch or intermittent wire failure off to the bin it goes. Ta!

 

[N00balicious]

I've seen patch cords go bad, because they've had a lot of use going in and out of sockets. Typically, the plastic clip on the patch cord that secures it in the socket is first to go. Then its RJ45 connector gets wobbly in the socket and has to be replaced.

However, a patch cord that has been immobile for a long time spontaneously failing is peculiar. At first guess, I would have thought there was a failure in the port or its electronics.

Glad you figured it out at low to no cost.

 

[PlasticExistence]

Have you considered the existence of gremlins?

 

[FranzJoseph]

Have you considered the existence of gremlins?

Now that I think of it, I did forget to sacrifice the annual black chicken this year!

 

[continuum]

We’ve got many customers with patch cables in old buildings, probably 30+ years old. Cables probably get touched every 5, 6, 7 years or so to refresh the switches in the wiring closets. So yes, we do see failures. A customer, a bit out of cycle, rearranged a bunch in one closet in particular for some new equipment they ordered and I think they had something surprising like three failures after doing so.

So yes. It does happen, but it’s also not common in normal use.

 

[Chanur64]

Reminds me of one cat5 cable I was using on consumer stuff. Worked fine for a year, router got moved for some rearranging in the room and some time afterwards I started noticing odd infrequent disconnection problems on the desktop. Skipping a lot of frustration (because I just assumed it was a "Windows" problem) I eventually realized that the connector piece itself wasn't quite right on the cat5 cable, there was a LOT of play in the thing. It latched just fine but even latched it would slide far enough out of the jack to fully disconnect as if it was unplugged, and I'd simply never noticed until I moved the router one too many times.

Tossed that cable to prevent future headaches but I don't look at cables the same way again regardless of if they latch into place or not. Didn't help I've seen one too many videos since then about how the most mass-produced cables can often have missing, skipped wiring in them and other shortcuts manufacturers take with them now.

 

[Quirinus]

Have you considered the existence of gremlins?

Gremlins another word for mice? /s (sorta)

I second the multimeter or a fluke tester for testing the cable. This feels like oxidation somewhere.

 

[FranzJoseph]

Gremlins another word for mice? /s (sorta)

I second the multimeter or a fluke tester for testing the cable. This feels like oxidation somewhere.

Had a pet rat who totally loved chewing through anything. Fucked up my first edition Hobbit book (a translated one, but now pretty rare nevertheless due to the cover art), among other books plus a few cables. Though she was a really smart and nice rat otherwise, which got her a full (albeit conditional) pardon (fuck up my books, and its almost the choosing‑the‑pans‑and‑condiments time if you aren't really nice).

 

[FranzJoseph]

Don't worry @PlasticExistence , I'd never harm a pet even if it chewed through an original Picasso ;-)

 

[PlasticExistence]

Don't worry @PlasticExistence , I'd never harm a pet even if it chewed through an original Picasso ;-)

Nor would I, but I'm upset about the Hobbit book for you.

 

[FranzJoseph]

Nor would I, but I'm upset about the Hobbit book for you.

Nah, it was honestly all my mistake for letting her out unsupervised. Plus at least the rat showed some rather good book taste in explicitly choosing The Hobbit, the little geek she was ;-)

That local Hobbit first translation edition was incidentally translated into my language by a family friend in the 1980s, and I still have another copy (plus some samizdat editions), so not that bad of a loss. Even if it currently sells at more than 100€ here.

The illustrations by a very gifted local artist were one of the best ones out there, even if much quirkier than most of the English editions' illustrations. I still see The Hobbit in terms of them, much unlike the Lee Alan illustrations or Jackson's films. And I feel they were more in line with that JRRT would have liked.

The moral of the story, even if your pets have great taste in books, better keep them out of your library

 

[Randomizer]

I've seen that happen, yes. In my experience, once a cable files like that, even if you move it around and get it to reconnect, there is a high chance that it may fail again soon, so in critical locations or hard-to-get-to places, I destroy the cable and replace it.

This goes for SAS/SATA cables, too. I've had many of those just suddenly start failing over the years and cause RAID arrays to drop drives. If I see read/write/CRC errors on a drive but the SMART report looks OK, it's most likely an issue with a cable, and replacing the cable has a >50% of resolving the issue. I've also had an HBA/RAID card go bad and start having weird issues but ONLY with a drive on a specific channel (always the 4th drive on the 2nd SAS port). I used it to control 7 drives for several years before finally replacing it. That one took a while to track down . . .