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In our new office all of our ethernet jacks are "double jacks" (two ethernet ports on one plate on the wall dual ethernet jack), each with their own CAT6 cable wired to a series of identical dual jacks (we didn't have time to order a patch panel) near the switch. We then use CAT5e cables to connect devices to the jacks on one end and the jacks to the switch on the other end.

We just plugged in a Samsung SCX-4848FN printer/scanner to one of the jacks and it works fine. However, the computer (WIN10 Pro) plugged into the jack next to it is suddenly losing connectivity (when we turn of the printer the problem goes away). The network interface shows as connected, but the machine cannot even ping the default gateway (which is a pfSense router plugged into the switch). Both machines are receiving different static IP assignments over DHCP from the router and the MAC addresses are different. The problem is resolved by disabling and re-enabling the network interface on the windows machine.

Could the problem possibly be caused by interference from the two network jacks next to each other (we have not yet had the ability to see what happens if we plug the printer into a jack located elsewhere)? If not, what else could possibly be causing this?

The only other thing I can think of is that when the guy wired the wall jacks, he wound the slack in the cables around the ports before securing the lid in the panel. I don't know if that would cause interference between the two cables...

closed as too broad by Ron Maupin Jul 18 '18 at 4:25

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    This sounds like a cable installation problem. Didn't your cable installer give you the test reports after installation? You should have the installer come back to fix this. Also, Category-5 is not longer a registered cable, and mixing categories (Category-5 patch cables on Category-6 horizontal cable) is not allowed, and it can lead to problems. – Ron Maupin Jun 1 '17 at 13:45
  • Sorry, I meant CAT5e, not CAT5 (I edited the question). The only testing that was done was with a simple cable tester after connecting the jacks on the two ends of each cable. – Aaron J Spetner Jun 1 '17 at 13:50
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    When installing cable, especially, Category-6 or Category-6a, you must use a real cable tester that is capable of performing the full category test suite. Cable installers must provide you the reports that you should keep on file. Even experienced installers can have problems installing Category-6 cable and get it to pass the test suite, and you probably have some problems that you don't know about. – Ron Maupin Jun 1 '17 at 13:53
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    @RonMaupin if he didn't have a patch panel in stock and had to resort to using wallports at the switch end I very much doubt he is the type of installer who would use proffesional test gear and provide the customer with a test report. – Peter Green Jun 1 '17 at 14:17
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    Unfortunately, if it is an installation problem, then there is really nothing we can do to help you. If it is a host problem (ethernet adapter), then it is off-topic here. @PeterGreen, a cable installer without the proper tools is worse than useless, and should not be hired (or should be fired). It would actually be unethical to professionally install cables and not run the test suite and provide the test reports to the customer. – Ron Maupin Jun 1 '17 at 14:31
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I would bet on shitty installation causing reduced signal quality and interference between the two ports. Cheap cable testers will tell you if a wire is open-circuit or connected to the wrong pin but won't really tell you anything beyond that.

The first thing I would do is unscrew the ports and inspect the terminations. If you see large amounts of untwisted wire then cut it off and re-terminate with the minimum possible amount of untwisting.

If you are still having problems then IMO it's time to call in a professional network installation firm who can test the work with high-end test gear and if needed re-do it.

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    With such an amount of crosstalk, I'd bet on pair mismatching - check whether the pairs are terminated exactly as they need be on both sides. – Zac67 Jun 1 '17 at 17:44

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