New cable modem - still not 100 Mbps

I started out with 50 Mbps and an Arris SB6141 cable modem. It would do the advertised speed. Then TWC upgraded everyone to 60 Mbps for free. The speed was as advertsed. Now Spectrum has upgraded (not free) everyone to 100 Mbps, and it not going much faster. It was between 60 and 80 Mbps - usually 65 Mbps. So I decided to take advantage of a coupon on Amazon and bought the Arris SB8200. It's DOCIS 3.1 with 32 down and 8 up channels. It's claimed to be capable of gigabit speeds. However, I'm getting a very steady 66 to 70 Mbps with 24 up channels and 4 down channels in use, I have all gigabit hardware and cables. When I copy files over the network, I have seen several hundred MB/sec through my router. Any ideas would be welcome.


Heres my SB8200 status dump:


The status listed show the connection state of the cable modem. They are used by your service provider to evaluate the operation of the cable modem.

Startup Procedure
Acquire Downstream Channel567000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
Configuration FileOK 
DOCSIS Network Access EnabledAllowed 

Downstream Bonded Channels
Channel IDLock StatusModulationFrequencyPowerSNR/MERCorrectedUncorrectables
9LockedQAM256567000000 Hz6.7 dBmV42.1 dB00
10LockedQAM256573000000 Hz6.5 dBmV41.8 dB00
11LockedQAM256579000000 Hz6.1 dBmV41.6 dB00
12LockedQAM256585000000 Hz5.6 dBmV41.4 dB00
13LockedQAM256591000000 Hz5.0 dBmV41.1 dB00
14LockedQAM256597000000 Hz4.4 dBmV40.8 dB00
15LockedQAM256603000000 Hz4.7 dBmV40.8 dB00
16LockedQAM256609000000 Hz5.4 dBmV41.2 dB00
17LockedQAM256615000000 Hz6.2 dBmV41.6 dB00
18LockedQAM256621000000 Hz7.2 dBmV42.2 dB00
19LockedQAM256627000000 Hz7.8 dBmV42.4 dB00
20LockedQAM256633000000 Hz8.2 dBmV42.6 dB00
21LockedQAM256639000000 Hz7.8 dBmV42.4 dB00
22LockedQAM256645000000 Hz8.1 dBmV42.6 dB00
23LockedQAM256651000000 Hz8.0 dBmV42.5 dB00
24LockedQAM256657000000 Hz8.2 dBmV42.6 dB00
25LockedQAM256663000000 Hz8.2 dBmV42.5 dB00
26LockedQAM256669000000 Hz8.1 dBmV42.5 dB00
27LockedQAM256675000000 Hz8.2 dBmV42.2 dB00
28LockedQAM256681000000 Hz7.8 dBmV42.3 dB00
29LockedQAM256687000000 Hz7.9 dBmV42.1 dB00
30LockedQAM256693000000 Hz8.1 dBmV42.4 dB00
31LockedQAM256699000000 Hz8.3 dBmV42.5 dB00
32LockedQAM256705000000 Hz8.3 dBmV42.5 dB00
1Not LockedOther0 Hz0.0 dBmV39.8 dB150

Upstream Bonded Channels
ChannelChannel IDLock StatusUS Channel TypeFrequencyWidthPower
184LockedSC-QAM37000000 Hz6400000 Hz43.6 dBmV
281LockedSC-QAM17800000 Hz6400000 Hz41.4 dBmV
382LockedSC-QAM24200000 Hz6400000 Hz42.1 dBmV
483LockedSC-QAM30600000 Hz6400000 Hz43.4 dBmV


Current System Time: Mon Mar 12 14:57:28 2018

Proven Sharer

Re: New cable modem - still not 100 Mbps

Does the router have QoS or bandwidth limitations set?

Are you running cloud backups, virus scans, software updates, etc. when speed testing?

Established Sharer

Re: New cable modem - still not 100 Mbps

How long was your modem running (before any power cycle and/or log reset)?  You need several hours (preferably six +) to get a good sample for trouble-shooting.

Re: New cable modem - still not 100 Mbps

I do have adaptive QoS set. I just tried it on and off, and find the results interesting. With adaptive QoS on, I just got a solid 80 Mbps, and with it off, I got 68 Mbps. Not what I expected.

Re: New cable modem - still not 100 Mbps

This new cable modem has been up for 17 hours. Maybe it will improve with time.


Re: New cable modem - still not 100 Mbps

Sorry but that modem isn't supported by Spectrum yet.... You're lucky it works at all. ...

Your 6141 should have done 100/10 just fine.

Did you reset the router to factory default then autodetect wan settings?


This is part of the issue and why it is not on the list:

1Not LockedOther0 Hz0.0 dBmV39.8 dB15




That's the ODFM channel for docsis3.1 use. It will take TWC/ Spectrum specific firmware and who knows when if ever they will pay to have it written. Right now they have major infrastructure issues with the 1 gig service due to the junk TWC sold them and it doesn't work well on the modem they provide in many areas.


Re: New cable modem - still not 100 Mbps

My SB6141 did not work just fine at 100/10 as it should have. This new SB8200 works a bit better - a little faster and much more steady. By steady I mean much more consistant speed. It is also interesting that the front panel of the SB8200 reports that DOCSIS 3.1 is engaged (at least the blue light is on which is supposed to mean that). It is obvious that the hardware sitting in the former TWC building a few miles from here may not be up to the marketing ambitions of Spectrum. 


In my research of cable modems I came across a number of people who have the SB8200 working somewhat OK with Spectrum in various parts of the USA. One of the marketing claims for the SB8200 is that it is compatible with DOCSIS 3.0 systems (at least on paper). Since it is working a bit better than my original cable modem, I'll keep it. Besides, how could I have said no to that Amazon coupon?


Re: New cable modem - still not 100 Mbps

If you couldn't make 100/10 with a 6141, you should of complained then rather than expecting a new modem to fix coaxial and overloaded  nodes... Especially if either was lower than 80%... they are overprovisioned for around 115/12.

If in NYS, contact your state atty gen... lotsa complaints there


BTW, the led's will not indicate anything correctly since it's a non approved modem...  All the LED's are programable and that modem does not have spectrum firmware in it, don't blame anything on them until they announce that as an approved modem. Good luck with any service calls until they do.

That odfm ch in the last slot should have a frequency and power level/ s/n listed, it shows correcteds indicating it has issues and probably slowing the normal docsis 3 channels down.