Ethernet cable only works on laptop

mshingler

Honorable
Apr 11, 2013
14
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10,510
I have a puzzling problem with my networking setup. I have router1 connected to my cable modem and a long ethernet cable that goes to my office (in another building) and connects to router2's WAN port to provide internet to the office. The internet stopped working in my office recently. At first, I thought router2 was bad so I replaced it. New router doesn't even recognize the cable as being connected. If I do the same set up with a different ethernet cable, I get a connection. Also, the cable is not recognized if I plug directly into my desktop - at the office. I even tried switching routers and got the same results. So, it would seem that my long ethernet cable to the office is bad. However, I can take the same cable and connect it to my laptop and get a perfect connection. What could be wrong with an ethernet cable that causes it to work in one computer but not another one?
 
How long is the cable? Standard Ethernet cables should only be used for 100m long runs, any more than that and you can face problems. Also look at how the cables are teminated (RJ45 Plugs) to see if they follow the standard pattern.
 
Likely either one of these issues:

Incorrectly terminated cable: If the cable was wired as a crossover cable (One end Type A and the other Type B), or if the brown or blue wires were not a good connection then a smarter nic would just correct the problem (or in the case of the brown/blue wire issue just reject it and run at 100mbps instead of 1000). Thus a device with the logic behind it could correct the issue, but others could not

Cable too long: The max length of cat5/cat6 is 300ft if you are getting near that then a weaker NIC could have trouble communicating.

Poor crimp on cable: There is also possibility that you have a poor crimp on the jack (pressing the little pins of the connector into each individual wire) so it works sometimes when it gets wiggled the "right" way, and doesn't other times.
 


Cable is under 300 ft. - about 250 or 275. Not sure how to tell if the plugs are wired by standard pattern.
 


The cable is outdoors - a direct bury cable, so I can't really put anything in between. I even tried switching out router1 and router 2 but that didn't help. Both routers are netgear.
 
Are the routers at right where the cable enters/exits the building.
I figured there was no way to put a device half way, but if the cable enters building B, goes up the wall and across the ceiling another 30-50 ft then you could attach a switch right where it enters the building.
 


The cable goes across the cellar about 25-30 feet before going out of building A. Only about 10-12 ft. in building B.
 
Ok, this is worth the shot for the $20-30 to do it.

Get yourself a metal switch from netgear, d-link, or trendnet.
First try plugging it in in between your long drop and router B. If that works then great.
Otherwise try accessing the cable as close as you can before it goes out of building A and put the switch in-line there.

If this does not work then you are going to have to pay for the expense of fiber.
There is always wifi but if you went through the trouble of burying cable I am assuming that wifi is insufficient bandwidth/latency for your needs
 
I would test your cable first a buried cable can easily be broken just by the soil settling on it. If the cable is in a pipe/conduit then maybe pulling a new cable through will fix you up. For the length of your run it would be best to use an STP (shielded) cable. But first test the existing cable. You can pick up a cheap cable tester from ebay for around 10 bucks or get one off the shelf for around 20.

If there are no breaks in the cable try re-terminating the cable at both ends. ensure that the cables are terminated in the proper way, (google the pin outs)