Arris SB6190 not supporting 400 Mbps

HowardSHowardS Posts: 4 ✭✭
in Connectivity Nov 27, 2020

We have an Arris SB6190 modem. A few months ago we tried to upgrade our Spectrum Internet service from 200 Mbps to 400 Mbps. According to Spectrum's website, this model supports the 400 Mbps speed. However, after we upgraded the service, we failed to get much more than 200 Mbps. We ran the speed tests from a computer that was directly connected to the modem via an Ethernet cord.

We spoke to a Spectrum technician, who ran a few tests and didn't see any problems. Since we couldn't get it to work, we reverted back to the 200 Mbps tier.

We would still like to get 400 Mbps if possible. Does anyone have any suggestions?


  • Lake802Lake802 Posts: 81 ✭✭✭✭
    Nov 28, 2020

    Hello Howard - sorry to hear you are having speed related issues. They are resolvable.

    The SB6190 is on the list of Spectrum approved devices at

    However, to resolve the issue , would encourage you to have Spectrum provide the modem and resolve any signal or provisioning issues that might be currently preventing you from reaching the higher speeds.

    You had exactly the right idea of testing at ethernet cord plugged straight into the modem. None of the speed tests are super accurate. It can be helpful if you use a new cat6a cable for the connection to the laptop to the modem for your testing.

    Ask the technician to verify that the new modem signal levels are in spec (RX, TX, SNR) and that there are no errors in the modem log (no T3, T4 or errors of any kind). that will help you get the speeds you are looking for.

    Please let us know how it goes after the technician visit.

  • HowardSHowardS Posts: 4 ✭✭
    Dec 06, 2020

    Thanks for the reply, but we're not comfortable with a technician visit because of Covid. The testing I mentioned was conducted with a Cat 6 cable. I was hoping someone on this message board might know why a supported modem didn't work at 400 Mbps, even though it works at 200 Mbps.

  • misterjmisterj Posts: 157 ✭✭✭✭
    Dec 06, 2020

    HowardS, I looked at the specifications on your modem and it should easily support 400 Mbps. Please go to

    test your speeds and post your results. You may well not need a new modem and getting one from Spectrum may block most access to the statistics. Please also post a screenshot of your signal levels and signal to noise (SNR) numbers. For the test please plug your computer directly into your modem. Cat 5E is plenty good for 1000 Mbps but it never hurts to go higher as long as the cable is not damaged. Please make sure you have a good piece of coax from wall to your modem. Thanks, John.

  • Lake802Lake802 Posts: 81 ✭✭✭✭
    Dec 06, 2020

    Greetings Howard - Your covid concerns are understandable. You can easily have them ship you a modem for testing purposes. They can verify the provisioning and provide further updates . They will be able to better support and diagnose a Spectrum provided modem when you are encountering temporary speed issues.

    The idea is to get the signals stable, reliable and provisioning verified. Eliminating the variable of your current modem can help get you closer to resolution.

    Nperf and the other internet speeds tests are not super accurate or all that helpful if the provisioning of your modem is incorrect or there are other signal issues / errors in the modem log.

    Please have them verify that all signals are in spec (RX, TX, SNR) , that the modem is provisioned correctly for the speed tier that you want, and that there are no T3 or T4 errors of any kind in the log.

  • misterjmisterj Posts: 157 ✭✭✭✭
    Dec 06, 2020

    HowardS, I disagree with Lake802 on nperf. I am suspicious of the Spectrum site, especially of the upstream speeds it reports. This is from my experience. As I have also observed, a few T3/T4 errors seem to indicate no real problems. I assume lots of errors will take you modem offline. It is nice to know what the counts are. John.

  • Lake802Lake802 Posts: 81 ✭✭✭✭
    Dec 07, 2020

    Greetings Howard - am grateful for the many insightful contributions of MisterJ. His good efforts have helped many on these forums. Its healthy and constructive to disagree on some things. There is nothing magic or super accurate about nperf or any of the speed tests. For some perspective , we ran each of the speed tests on a Spectrum modem that was provisioned for the 400Mbs Ultra service. The main issue is that the modem was provisioned correctly , signals were in spec and no errors of any kind in the logs.

    Have a look at the results:

    The key take away here is that none of the tests are super accurate. There are lots of other variables that influence the results you see - so the speed tests themselves are not really a good indicator or diagnostic of how things are going on your modem.

    In contrast, T3 and T4 errors are definitively service impacting. A few may be harmless (duration of a single T3 about 200 ms.) but T3 and T4 will generally increase in frequency and severity if the underlying causes of them are not corrected.

    The common sources of T3 and T4 errors are often outside the home so it is often possible to get them corrected and still be respectful of your articulated covid concerns.

    Main issue is that MisterJ , me and all of us on these forums just want to see you have stable, reliable connection that works at the provisioned speeds you are paying for.

    Would still encourage you to get modem swapped out, Have Spectrum verify signals (RX, TX, SNR) are in spec and also no T3 or T4 errors or errors of any kind in new modem log.

    It is likely Spectrum tech support can get this issue promptly resolved for you and still respect your covid concerns.

  • misterjmisterj Posts: 157 ✭✭✭✭
    Dec 07, 2020

    Lake802, that mess you posted makes no sense at all to me. The numbers are all over the place with no consistency at all. I now see why you tell everyone about unreliable testing sites. I have a 200Mbps plan running on an SB8200. It measures VERY consistently at 235 Mbps down and 9-10 Mbps up. If it varies much from these numbers, I start looking for problems. I certainly do not use 8 different sites and wonder what is true. Thanks, John.

  • Lake802Lake802 Posts: 81 ✭✭✭✭
    Dec 08, 2020

    @MisterJ Kindly review forum guidelines for "Be polite and courteous"

    Characterizing objective test results as a "mess" doesnt help the original poster and is not really in spirit of forum golden rule of keep your comments positive and constructive.

    Goal in sharing test results with Spectrum community is for folks to be aware more that there are lots of variable that affect perceived speeds.

    The links were included for some of the common speed tests so that people can independently confirm test results in the unique environment of their local settings.

    With a surge in folks working from home due to covid - there has also been a spike in VPN use. Test results were included so the result could be contrasted with and without VPN usage.

    Test results also include a contrast of work laptop versus home laptop. Results showed a home laptop with a $15 amazon basics connector far outperforming work laptop with a built in ethernet connector. So the local hardware being used to conduct the tests makes a significant difference in many cases.

    The tests were also conducted across multiple speed tiers including a docsis 3.1 modem and and a 1Gbps fiber connection. Some of the speed tests results became dramatically less accurate at the higher speed tiers.

    In the spirit of positive and constructive exchange of ideas in these forums, am optimistic that differing points of view can be accommodated while still keeping discussion polite and professional.

    If you offer folks recurring advice to try a 3rd party website like nperf, be open to the possibility that not everyone will agree with that especially if accuracy of nperf and other sites deteriorates at higher speed tiers and doesnt correlate well to actual modem health.

    Similarly, when you offer a subjective opinion of being "suspicious" of Spectrum speed tests especially the upload stats - others have a different view as to the voracity of that when objective test results show the upload stats to being nearly statistically identical across multiple apps and platforms.

    Main goal remains unchanged - am hopeful information provided will help original poster, Howard get the 400Mbs speed tier he is looking for with stable reliable signal.

  • misterjmisterj Posts: 157 ✭✭✭✭
    Dec 08, 2020

    Lake802, kindly: No thank you!

  • HowardSHowardS Posts: 4 ✭✭
    Dec 20, 2020

    I didn't mean to create such a controversial thread. For what it's worth, I did the nPerf test, but remember that I currently only subscribe to the 200 Mbps tier. As I posted above, since I wasn't getting the 400 Mbps speed, I reverted back to the 200 Mbps tier. Here are the nPerf results:

    Download: 236.1 Mbps

    Upload: 11.71 Mbps

    Latency: 16.00 ms

  • Lake802Lake802 Posts: 81 ✭✭✭✭
    Dec 20, 2020

    Greetings Howard - Thanks for the update. There is no significant controversy. Main goal was to share constructive info and help you get stable/reliable signal while also respecting your covid concerns on tech visit.

    Kindly let us know if you decide to try again on the 400Mbs speed tier. Tech glitches/signal issues are definitely resolvable.

  • HowardSHowardS Posts: 4 ✭✭
    Dec 27, 2020

    We just upgraded to the 400 Mbps tier to try it again. This time we are getting better results, although not consistently above 400 Mbps.

    Spectrum speed test results:

    1st attempt: 428.9 Mbps download/23.7 Mbps upload

    2nd attempt: 335.8 Mbps download/23.8 Mbps upload

    The nPerf results are as follows:

    1st attempt: 401.24 Mbps download/23.32 Mbps upload

    2nd attempt: 333.0 Mbps download/23.24 Mbps upload

    Are these the results expected at the 400 Mbps tier? They are certainly better than the last time we upgraded, when we didn't get much over 200 Mbps.

  • misterjmisterj Posts: 157 ✭✭✭✭
    Dec 27, 2020

    HowardS, I have 200 Mbps service and get a consistent 235 Mbps on

    I would expect you to get a consistent ~470Mbps. Enjoy, John.

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