CAT 6 only getting 100 megabits

3

Using a 200 foot CAT 6 cable I'm only getting 100 megabits on a 400 megabit connection. We tested a laptop and got about 370 megabits while directly connected to the modem (not a combination with router).

  • Modem tested directly capable of at least 370 megabits (not concerned about hitting 400 exactly).
  • No packet loss (ping google.com -n 20).
  • Good ping (17ms).
  • Updated network adapter drivers several times, no effect.
  • Cable is 200 feet though signal degradation doesn't occur until 100 meters (328 feet). Unknown if it is CAT 6 or CAT 6A - the former of which supports only 55 meters/180 feet).
  • Router software reports no errors of any kind.
  • Network Map: Modem to router, router to PC.
  • No VPN/proxies being used.
  • Testing at https://speedsmart.net/ yields numbers very close or directly at 100 megabits unlike ISPs who will give you an extra 2~5% extra speed.
  • I do not have a crimp tool or cable testing tool, a friend might.

There is only one oddity. Earlier today I found that the Internet on my desktop would occasionally disconnect outright. I used some needle-nose pliers to press the clip down as it was apparently pushing the jack away from the contacts in the physical port (that issue is now fixed). This did not effect the speed before or after. The cable was purchased by a friend on Amazon and it was ordered brand new. I can certainly live with 100 megabits after being stuck on two megabits this past summer though in the future is this issue arises it will effect more than my desktop work station. Suggestions please?

I grabbed a copy of JPerf and I'm not entirely sure what the results are telling me here:

JPerf Results

bin/iperf.exe -s -P 0 -i 1 -p 5001 -f k
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[180] local 192.168.0.190 port 5001 connected with 192.168.0.195 port 50509
[ ID] Interval       Transfer     Bandwidth
[180]  0.0- 1.0 sec  2016 KBytes  16515 Kbits/sec
[180]  1.0- 2.0 sec  1800 KBytes  14746 Kbits/sec
[180]  2.0- 3.0 sec  1808 KBytes  14811 Kbits/sec
[180]  3.0- 4.0 sec  2008 KBytes  16450 Kbits/sec
[180]  4.0- 5.0 sec   896 KBytes  7340 Kbits/sec
[180]  5.0- 6.0 sec  1384 KBytes  11338 Kbits/sec
[180]  6.0- 7.0 sec  1304 KBytes  10682 Kbits/sec
[180]  7.0- 8.0 sec  1168 KBytes  9568 Kbits/sec
[180]  8.0- 9.0 sec   792 KBytes  6488 Kbits/sec
[180]  9.0-10.0 sec  1536 KBytes  12583 Kbits/sec
[180] 10.0-11.0 sec  1480 KBytes  12124 Kbits/sec
[180] 11.0-12.0 sec  1328 KBytes  10879 Kbits/sec
[180] 12.0-13.0 sec  1312 KBytes  10748 Kbits/sec
[180] 13.0-14.0 sec  1408 KBytes  11534 Kbits/sec
[180] 14.0-15.0 sec  1440 KBytes  11796 Kbits/sec
[180] 15.0-16.0 sec  1424 KBytes  11665 Kbits/sec
[180] 16.0-17.0 sec  1512 KBytes  12386 Kbits/sec
[180] 17.0-18.0 sec   792 KBytes  6488 Kbits/sec
[180] 18.0-19.0 sec  1488 KBytes  12190 Kbits/sec
[180] 19.0-20.0 sec  1432 KBytes  11731 Kbits/sec
[ ID] Interval       Transfer     Bandwidth
[180] 20.0-21.0 sec  1616 KBytes  13238 Kbits/sec
[180] 21.0-22.0 sec  1432 KBytes  11731 Kbits/sec
[180] 22.0-23.0 sec  1264 KBytes  10355 Kbits/sec
[180] 23.0-24.0 sec  1600 KBytes  13107 Kbits/sec
[180] 24.0-25.0 sec  1480 KBytes  12124 Kbits/sec
[180] 25.0-26.0 sec  1456 KBytes  11928 Kbits/sec
[180] 26.0-27.0 sec  1360 KBytes  11141 Kbits/sec
[180] 27.0-28.0 sec  1432 KBytes  11731 Kbits/sec
[180] 28.0-29.0 sec  1392 KBytes  11403 Kbits/sec
[180] 29.0-30.0 sec  1488 KBytes  12190 Kbits/sec
[180] 30.0-31.0 sec  1576 KBytes  12911 Kbits/sec
[180] 31.0-32.0 sec  1496 KBytes  12255 Kbits/sec
[180] 32.0-33.0 sec  1344 KBytes  11010 Kbits/sec
[180] 33.0-34.0 sec  1376 KBytes  11272 Kbits/sec
[180] 34.0-35.0 sec  1520 KBytes  12452 Kbits/sec
[180] 35.0-36.0 sec  1520 KBytes  12452 Kbits/sec
[180] 36.0-37.0 sec  1368 KBytes  11207 Kbits/sec
[180] 37.0-38.0 sec  1432 KBytes  11731 Kbits/sec
[180] 38.0-39.0 sec   856 KBytes  7012 Kbits/sec
[180] 39.0-40.0 sec  1496 KBytes  12255 Kbits/sec
[ ID] Interval       Transfer     Bandwidth
[180] 40.0-41.0 sec  1600 KBytes  13107 Kbits/sec
[180] 41.0-42.0 sec   392 KBytes  3211 Kbits/sec
[180] 42.0-43.0 sec  1312 KBytes  10748 Kbits/sec
[180] 43.0-44.0 sec  1480 KBytes  12124 Kbits/sec
[180] 44.0-45.0 sec  1464 KBytes  11993 Kbits/sec
[180] 45.0-46.0 sec  1312 KBytes  10748 Kbits/sec
[180] 46.0-47.0 sec  1608 KBytes  13173 Kbits/sec
[180] 47.0-48.0 sec  1408 KBytes  11534 Kbits/sec
[180] 48.0-49.0 sec  1256 KBytes  10289 Kbits/sec
[180] 49.0-50.0 sec  1040 KBytes  8520 Kbits/sec
[180] 50.0-51.0 sec  1360 KBytes  11141 Kbits/sec
[180] 51.0-52.0 sec  1368 KBytes  11207 Kbits/sec
[180] 52.0-53.0 sec  1184 KBytes  9699 Kbits/sec
[180] 53.0-54.0 sec   992 KBytes  8126 Kbits/sec
[180] 54.0-55.0 sec   456 KBytes  3736 Kbits/sec
[180] 55.0-56.0 sec  1080 KBytes  8847 Kbits/sec
[180] 56.0-57.0 sec   640 KBytes  5243 Kbits/sec
[180] 57.0-58.0 sec  1240 KBytes  10158 Kbits/sec
[180] 58.0-59.0 sec  1304 KBytes  10682 Kbits/sec
[180] 59.0-60.0 sec  1448 KBytes  11862 Kbits/sec
[ ID] Interval       Transfer     Bandwidth
[180] 60.0-61.0 sec  1024 KBytes  8389 Kbits/sec
[180] 61.0-62.0 sec   728 KBytes  5964 Kbits/sec
[180] 62.0-63.0 sec   736 KBytes  6029 Kbits/sec
[180] 63.0-64.0 sec  1088 KBytes  8913 Kbits/sec
[180] 64.0-65.0 sec  1040 KBytes  8520 Kbits/sec
[180] 65.0-66.0 sec  1016 KBytes  8323 Kbits/sec
[180] 66.0-67.0 sec  1104 KBytes  9044 Kbits/sec
[180] 67.0-68.0 sec   984 KBytes  8061 Kbits/sec
[180] 68.0-69.0 sec  1344 KBytes  11010 Kbits/sec
[180] 69.0-70.0 sec  1120 KBytes  9175 Kbits/sec
[180] 70.0-71.0 sec  1400 KBytes  11469 Kbits/sec
[180] 71.0-72.0 sec  1400 KBytes  11469 Kbits/sec
[180] 72.0-73.0 sec   920 KBytes  7537 Kbits/sec
[180] 73.0-74.0 sec  1176 KBytes  9634 Kbits/sec
[180]  0.0-74.6 sec  96680 KBytes  10621 Kbits/sec
[320] local 192.168.0.190 port 5001 connected with 192.168.0.195 port 50510
[ ID] Interval       Transfer     Bandwidth
[320]  0.0- 0.0 sec  8.00 KBytes  6554 Kbits/sec
Done.

My network adapter is a Realtek PCIe GbE Family Controller. We plugged in the wire to my laptop and hit 450 megabits (that might be sufficient, right?). He is lending me his Broadcom controller and I hit 433 Mb. My laptop tested at 455 Mb so the issue is not with the cable.

My current conclusion: the NIC might somehow be damaged or improperly configured. I was getting ~200 Mb at the last place on that Realtek NIC. Perhaps this question might at least help someone troubleshoot their own trouble.

John

Posted 2018-11-01T22:43:29.053

Reputation: 1 490

Is the network adapter on your computer set for 100Mbps or 1Gbps? Check the status of it to make sure it's actually running at 1Gbps. – HazardousGlitch – 2018-11-01T23:50:09.303

1This is nowhere near a 1 Gbps link speed. I agree with @Hazard. Make sure both NICs have negotiated a 1 Gbps link. Don't forget to run this test across a shorter cable as a control/comparison test. – I say Reinstate Monica – 2018-11-02T00:25:50.693

@TwistyImpersonator How do I ensure that they have negotiated a 1 Gbps link? – John – 2018-11-02T00:43:32.437

1

That depends on your OS. Try doing a Google search along the lines of change network adapter negotiated link speed on 'Insert OS here'

– I say Reinstate Monica – 2018-11-02T00:46:49.520

I would strongly recommend against changing the negotiated speed. If the adapters don't negotiate 1 Gbps by themselves, you already have physical problems to solve first. – user1686 – 2018-11-02T05:12:27.720

@grawity Good point. To clarify, I suggested those search terms to help the OP confirm the link speed, not change it from what's been negotiated. – I say Reinstate Monica – 2018-11-02T10:51:50.220

Is the cable indoors or outside because outside cabling requires different insulation. Are there any sources of EMI of EFI along the 200ft route? – cybernard – 2018-11-02T14:41:25.533

Answers

2

If you don't have access to cable validation tester, use a throughout testing tool such as iPerf3 to test the throughout of the 200 ft. cable using two directly-connected computers, one on each end. Perform the same exact test with the two computers using a short, known-good cable and compare the results.

Doing this will help establish the maximum throughout supported by the long cable, as well as shed light on whether it's performing to spec (it should give very comparable results to the short cable).

If the cable checks out, this lets you know one of the other devices in the link is playing a role in your problem. Conversely, if the cable gives bad results, you should replace it.

Example usage of iPerf for this test:

On Computer A start iPerf in server mode:

iperf -s

On Computer B start a default test which transmits data to Computer A:

iperf -c <IP_of_Computer_A>

For a more thorough explanation of how to use iPerf to determine the maximum throughput of a link see this Super User answer.

I say Reinstate Monica

Posted 2018-11-01T22:43:29.053

Reputation: 21 477

I tried looking up the documentation and am having trouble with it (you didn't post any command line examples). This requires one computer acting as a server and the other as a client with the network cable plugged in to each computer. I have my laptop and desktop directly connected at each end. Also, besides the command line commands, I do't believe so, though do I have to have one of the computers connected for this to work? – John – 2018-11-01T23:36:12.907

1@John I'll edit with some example commands when I get off mobile. As for "one of the computers connected," do you mean to the Internet? If so, the answer is no. You should only have them connected to each other via the cable. – I say Reinstate Monica – 2018-11-01T23:41:15.633

I was only able to get it working when I added a WIFI adapter to get the Desktop on a network environment. Unfortunately I'm not sure how networking works (if at all) and it's kinks when it's two computers only connected directly together via the CAT 6E cable. I posted the results though I'm not sure how to interpret them. – John – 2018-11-02T00:16:07.703

2

Using a 200 foot CAT 6E cable...

There is no such thing. You may be thinking about Category-5e. If someone is selling Category-6e, it is a junk cable.

In any case, 1000Base-T (1 Gbps) requires all four pairs to connect at 1 Gbps. If there is a problem with one or more pairs, it tries to fall back to 100Base-TX (100 Mbps). Every time I hear about a problem like yours, it has been a cable problem.

Ron Maupin

Posted 2018-11-01T22:43:29.053

Reputation: 3 130

This is a good point, however, we don't know it is a junk cable, only that it's a mislabeled cable. – I say Reinstate Monica – 2018-11-02T11:23:06.880

Nope, it's CAT 6. Not sure why my friend said 6E. Fixed my post to reflect this. Also the exact same wire works great (450Mb) on the laptop and connected to the addon Ethernet card so I think at this point the problem most likely is with the onboard NIC. – John – 2018-11-02T22:10:10.630

0

If the modem can deliver 370 Mbps with the laptop I would check if your router do DPI, as such, to support a 400 Mbps link with DPI you need a really high-end router.

I would test with the laptop and the 200 foot cable run to be sure.

I would disable DPI if it's in use in the router, or I would test with a SOHO router in worst case, as such router can deliver a high throughput as it scan nothing.

yagmoth555

Posted 2018-11-01T22:43:29.053

Reputation: 258

Asked: 2018-11-01T22:43:29.053

Viewed: 150 times

Active: 2018-11-02T22:19:50.643