Network cable not working, but tests okay

I have a Cat6 network cable that doesn't seem to work in my switch or router. The cable in question is running within the walls of the building, so it's not as simple as just switching out the cable.
I put a new end on the cable. I've used a network tester that plugs into both ends of the cable and runs through each strand 1-8 and lights up on the tester. All 8 lights come on in sequence at both ends. But when I plug the cable into the switch or the router, the lights on the front of the switch or router don't light up for the jack I plug it into. I've plugged other cables into the open jacks, and the lights come on correctly. I've plugged the cable into multiple jacks on the switch and an open jack on the router. So I'm confident the issue is in the cable. But since the tester lights up all eight lines, i'm not sure where else the issue could be. The cable worked yesterday. But then I was "cleaning" up the cable box and it stopped working. I suspected that i messed up the jack, so that's when i put a new jack on the cable. I've put two new jacks on it, so i don't think a faulty jack is the issue.
Any ideas or suggestions?
lyonskiAsked:
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Steven CarnahanNetwork ManagerCommented:
You don't mention if you made sure there was a device (computer, printer, etc) connected at one end?  Have you checked that the NIC in the device isn't the culprit?
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KromptonCommented:
Testers can have more power to put through the individual strands. This can mask a slight flaw by overcoming the resistance from an "almost break."

Does your tester have the capability of reporting any resistance spike and it's location along the cable? Not all testers can tell you where a break is in a cable. The ones that can tend to be pricey.

Is it correct that the switch and router you tried with the Cat6 cable do work in other locations? If unknown, I would test them elsewhere to confirm.

After that, if you have sufficient extra cable, I would replace the connectors once more. It sounds like your first cable ends worked, then one was possibly damaged inadvertently, then your replacements did not work. It is possible that one of the ends was flawed resulting in sufficient connection for tester but not for your switch.

Let us know what you find.

Cheers,
Krompton
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lyonskiAuthor Commented:
I don't see anything on my tester that would allow it to report a resistance spike. The switch and router do work with other cables. I have tried two new cable ends. Not sure if trying a third would do the trick.
The cable is connected to a tv at the other end.
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Larry Struckmeyer MVPCommented:
Can you verify that the cable in the wall begins in a fixed wall jack (female) and ends in a fixed patch panel (also female)?  

Or, is it male on both ends?  If male on both ends and you have others that work, examine the one that works carefully to see the color pattern inside the male connector.  Verify the one you are concerned about matches the others.
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lyonskiAuthor Commented:
The cable in the wall begins in a fixed wall jack and ends with a male end. I have compared the color pattern in other cables that work and it is the same. ALSO - the tester lights up 1, 2, 3, 4, 5, 6, 7, 8. If i had the wires inserted into the male jack in the wrong order, the lights on the tester would come on in some other order.
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CompProbSolvCommented:
It sounds as if your tester is just doing a simple continuity test (at DC).  Failing such a test would be a clear indication that the cable does not have all 8 wires connected correctly.  Passing such a test would NOT absolutely indicate that it can be used for Ethernet.  There are other parameters (interference, crosstalk, resistance, length, etc.) that could be the issue.  While I have found it rare that these will keep an LED from illuminating, I could imagine that it is possible.

As a general rule, you'll be much better off with a female jack on either end of any cable running through the walls and a patch cable used between the jack and the device (router, switch, computer, etc.), though that is likely not the issue here.

You mention that one end is connected to a TV.  Have you confirmed that this jack is active?  A very useful troubleshooting tool is a long (would 100' be long enough?) known good cable.  You could temporarily connect this between the TV and the switch or router to confirm that cabling is really the issue.
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enrmmobaCommented:
the lights on the switch only comes on when the other end is actually connected to a device.

i would use a short cable and connect a laptop / PC  directly to the switch port in question right at the cabinet, issue might not be with the cable at all.
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Larry Struckmeyer MVPCommented:
Can't speak for your tester, but the Ethernet spec is usually 1- Orange/white,- 2-Orange, 3--Green/White-, 4-Blue/White-, 5-Blue-, 6-Green-, 7-Brown/White-,8-Brown-.    Thus I would expect the tester to show 1,2,3,6,4,5,7,8

By using male at one end and female at the other you have caused a warp in the space time continuum and maybe opened a worm hole.  

If the port on either end is sensitive to this the LEDs will not power on and no connection is made.

Try adding a female at the switch end, punching down in the same pattern as the TV end,  and using a short patch cable from that to the switch.
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CompProbSolvCommented:
@Larry:
Don't overlook that there are two different Ethernet specs: T568A and T568B.  Your example is the T568B spec.  The critical pairs 1/2 and 3/6 are reversed between them.  Using both standards (one on either end) should show up as a problem with his tester.

Using a male connector at one end and female at the other also shouldn't create an immediate problem as long as they are appropriately wired.  The devices at either end would never know the difference.
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Larry Struckmeyer MVPCommented:
@CompProbSolv

Agreed.  But afaik  T568A is seldom used and just gives anyone reading this more complexity.
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Christopher Raymond MendozaCommented:
We use network testers similar to yours to check for continuity and nothing more. The LEDs inform us that the individual wires are not broken. What it does not inform us about is the quality of the signals that pass through the same.

When we encounter similar problems we first check the ends (connectors) and do visual inspection of where the cable and where it passes through, if possible. More so if we had the cable(s) installed by a third party.

Our last resort is to contact a consultant who checks the cable using a (pricey) network and bandwidth tester that does more than continuity tests.
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KromptonCommented:
Has there been any progress made?

Krompton
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lyonskiAuthor Commented:
Hmmm...I entered an explanation of what I ended up finding several days ago, but don't see it in here.
I discovered that the 8 lights on the tester would light up only if I was holding the jack firmly into the tester. If I let go of the jack, only 7 of the 8 lights would come on. So I put on another jack, and now it works.
Thanks all for your help!
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