Observer

Thoughts on my signal? Widely varying download speeds.

Hi first time poster here.  I am on the 20MBPS TW plan and have my own Motorola SB6141 modem which has been working fine as far as I know. Recently (last week or two) I have noticed occasional sluggish performance but it is very sporadic. I'll run a speed test one minute and get download speeds in excess of 20MBPS.  Five minutes later, I'll run it again with no changes and get much lower, in some case down in the 2-3MBPS range. Upload speeds seem to be consistently above 2MBPS.

 

I don't know if the issue is with the modem or with my Netgear Nighthawk because the speed issue is unpredictable and inconsistent. The only coax coming into the house goes straight to the modem, and I have made no network changes intenally.  

Here's the screenshot from the Signal Page.  Does anyone recongnize any issues? I have not called TW yet because I want a little insight from those who know how to interpret these numbers.  From what I have read, signals and SNR appear to be within spec tough the dowload reading may be a bit on the low end.  Any insight is appreciated.

 

This page provides information about the current upstream and downstream signal status of your Cable Modem.

 

DownstreamBonding Channel Value
Channel ID25 23 26 27 28 29 31 32 
Frequency723000000 Hz 711000000 Hz 729000000 Hz 735000000 Hz 741000000 Hz 747000000 Hz 759000000 Hz 765000000 Hz 
Signal to Noise Ratio36 dB 36 dB 36 dB 36 dB 36 dB 36 dB 36 dB 36 dB 
Downstream ModulationQAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 
Power Level
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
-5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -6 dBmV  

 

UpstreamBonding Channel Value
Channel ID66 65 67 68 
Frequency24200000 Hz 19400000 Hz 30600000 Hz 37000000 Hz 
Ranging Service ID12309 12309 12309 12309 
Symbol Rate5.120 Msym/sec 2.560 Msym/sec 5.120 Msym/sec 2.560 Msym/sec 
Power Level40 dBmV 39 dBmV 40 dBmV 40 dBmV 
Upstream Modulation[3] QPSK
[3] 16QAM
 
[3] QPSK
[2] 16QAM
 
[3] QPSK
[3] 16QAM
 
[3] QPSK
[3] 16QAM
 
Ranging StatusSuccess Success Success Success 

 

Signal Stats (Codewords)Bonding Channel Value
Channel ID25 23 26 27 28 29 31 32 
Total Unerrored Codewords2303503847 2303487700 2303496054 2303479154 2303469757 2303471718 2303472737 2303473119 
Total Correctable Codewords26 120 15 12 18 23 
Total Uncorrectable Codewords1527 671 602 684 1533 630 706 1362 
24 REPLIES 24
Proven Sharer

Re: Thoughts on my signal? Widely varying download speeds.

The higher number of uncorrectable errors on DS channels 25, 28, and 32 points to some intermittent interference caused by signal leakage from local TV broadcasts and/or 4G LTE cell phone systems.  This could be from a loose cable connector anywhere in your indoor cabling or outside flexing in the wind, or by a now-unused cable connected to a splitter. 

 

The good news is that you can remove and then re-tighten the indoor fittings yourself using a 7/16" wrench, without help from TWC.  They need to be snug, but don't overtighten!  It is possible to snap them off, so just use your little finger on the wrench.  Any corroded cable, corroded or loose connectors or splitters do need to be replaced by TWC.

 

If you find that everything is already tight and shiny, or if tightening up a few fittings gets the uncorrectables down to a few hundred and not increasing after a power cycle, that's great.   Let us know what you find.

 

Observer

Re: Thoughts on my signal? Widely varying download speeds.

Thanks Karl.  The connections look ok.  I have now taken the Netgear Nighthawk R7000 router out of the picture and only have my laptop hooked to the router.  I have done several speed tests I'm getting better than advertised speeds (22oooMBPS+), but since my issues have been sporadic, I'm not ready to draw any conclusions yet.  I powered off/on the modem to get it to recognize the router was replaced by my laptop (is there a better way), and the new "codewords" section shows three channels reads as follows:

Signal Stats (Codewords)Bonding Channel Value

Channel ID25 24 27 28 29 30 31 32 
Total Unerrored Codewords64747215 64755962 64763795 64771805 64739164 64740169 64741341 64741711 
Total Correctable Codewords15 11 15 19 18 
Total Uncorrectable Codewords706 561 1358 1537 702 797 716 1419 
Valued Contributor

Re: Thoughts on my signal? Widely varying download speeds.

you could simply try your own signal amplifier;

https://www.amazon.com//dp/B001BMKNZI

this will raise your down power levels without

increasing your up power levels.

 

 

Proven Sharer

Re: Thoughts on my signal? Widely varying download speeds.

Hi Buzz -

You (still) have three channels [DS27, 28, & 32] with uncorrectable error counts already over 1000 in just a few hours.  If those stay put you might be OK and still get 20D/2U speeds. 

 

Channel 28 is the frequency slot for Verizon's nationwide 4G LTE network sites.  If that error count climbs, the cable network definitely has a leak and TWC will probably need to roll a bucket truck crew to locate and repair.  First check all the connectors in your cable installlation, but  understand the leak isn't necessarily inside  your home.  It could be a drop cable in your neighborhood scraping against a tree, or a loose connection anywhere along the trunk line.

 

Don't mind the cynic who thinks he can engineer cable subscriber installations better than TWC folks who just break things, though judging from a few recent forum cases he could be right.  I'm just noting that your up and down levels don't correlate with the patterns we see for most home installs, and one potential cause.

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Participant

Re: Thoughts on my signal? Widely varying download speeds.

You don't want to amplify signal to a modem. that's a bad idea. 

Expert

Re: Thoughts on my signal? Widely varying download speeds.

I suspect the modem is not on the first 2 way splitter for a start. Looks like a 4 way or 2-2ways in series. Amplifiers are bad in a case like yours.

 If you are internet only, there should be NO SPLITTERS.

 

 Nexty issue, try turning off IPv6 and verify no devices are running cloud, sync, onedrive, dropbox or Microifts illegal use of your computer to do other customers Win 10 upgrades... Cnet has info on turning that off.

 

Expert

Re: Thoughts on my signal? Widely varying download speeds.

711 mHz is an AT&T 4G phone getting into the modem. Verify all connections are a tad more than finger tight and with compression, not molded or crimped connectors including the backsides of wall plates. There cannot be any open splitter ports or stubs of cable off to unused locations. wall plates.

Keep your 4G phone 5-10' away from the modem as well as any 3g 4g modem equiped devices like Cpap machines and heart monitors.

 

Observer

Re: Thoughts on my signal? Widely varying download speeds.

Thanks for the replies.  I have no splitters inside the house.  I'm not sure what it looks like at the street (all underground utilities here).   I'll look for that Cnet article.

 

I am beginning to think that the problem may be with my router (despite any leakage/uncorrected codewords).  I have not been able to duplicate the slow speed when connected directly to the modem, but since I have to reboot the modem everytime I switch between a router connection and a direct connection, it's hard to say since a modem reboot seems to alway temporarily fix the problem anyway.

 

I made the dreaded call to TW tech support last night, and as suspected, he told me that everything "looked good" on their end and since it's a customer owned modem/router, good luck. He did suggest that since the merger with Spectrum, he could transfer me to sales and upgrade me from 20 to 60MBPS with a new modem included for $5 less per month.  Cool.  Sales basically told me, "Teah, not so fast. That love is only for new customers, not you."

Expert

Re: Thoughts on my signal? Widely varying download speeds.

Look in the outside boxes.

 Are there cable outlets in other rooms?

I'll bet there's a 4 way somewhere.  -6 is awfully low for a single connection.

 This is not a modem issue, it's TWC's blame it on the coam device business posture.Robot Sad