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CM1000 not getting Gigabit speed with Xfinity

RandomName1
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CM1000 not getting Gigabit speed with Xfinity

The Xfinity tech showed upwards of 1 Gig from the wall but I can't get a gig connected directly to the CM1000 modem. Please help.

Model: CM1000|Ultra-High Speed Cable Modem—DOCSIS® 3.1 Ready
Message 1 of 12
plemans
Guru

Re: CM1000 not getting Gigabit speed with Xfinity

What speed are you getting? 

What device are you testing on? 

What website are you using for test?  (if its speedtest.com, try several of their servers, they don't always pick one that can max out the speed). Try speedtest.xfinity.com

Current Setup: CM2000-> SXK30-> GS716v2-> RAXE500->
Message 2 of 12
Gpai
Aspirant

Re: CM1000 not getting Gigabit speed with Xfinity

I am having similar issues. I recently upgraded to gig speed through comcast. The engineer came and tested with his equipment and he was getting gig speed whereas I was not able to through my CM1000.

The version of Firmware is V7.01.01

The connection says Good

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency

<tabindex=-1>Startup Procedure</tabindex=-1>

ProcedureStatusComment
Acquire Downstream Channel651000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
SecurityEnableBPI+
IP Provisioning ModeHonor MDDIPv6 only

<tabindex=-1>Downstream Bonded Channels</tabindex=-1>

ChannelLock StatusModulationChannel IDFrequencyPowerSNR / MERUnerrored CodewordsCorrectable CodewordsUncorrectable Codewords
1LockedQAM25637651000000 Hz3.5 dBmV39.7 dB3538317600
2LockedQAM25610483000000 Hz4.4 dBmV41.6 dB3422723100
3LockedQAM25611489000000 Hz4.6 dBmV41.6 dB3423064100
4LockedQAM25612495000000 Hz4.7 dBmV41.6 dB3423448000
5LockedQAM25613507000000 Hz5.6 dBmV41.8 dB3423822400
6LockedQAM25614513000000 Hz6.0 dBmV41.8 dB3424248500
7LockedQAM25615519000000 Hz6.6 dBmV42.0 dB3424595400
8LockedQAM25616525000000 Hz7.0 dBmV41.9 dB3424992900
9LockedQAM25617531000000 Hz7.5 dBmV42.0 dB3425352000
10LockedQAM25618537000000 Hz8.1 dBmV41.9 dB3425738000
11LockedQAM25619543000000 Hz8.4 dBmV41.9 dB3426013900
12LockedQAM25620549000000 Hz8.6 dBmV42.0 dB3426472400
13LockedQAM25621555000000 Hz8.3 dBmV41.6 dB3426883800
14LockedQAM25622561000000 Hz7.7 dBmV41.6 dB3427231000
15LockedQAM25623567000000 Hz7.0 dBmV41.5 dB3427563300
16LockedQAM25624573000000 Hz6.3 dBmV41.5 dB3427932200
17LockedQAM25625579000000 Hz5.8 dBmV41.5 dB3428643500
18LockedQAM25626585000000 Hz5.2 dBmV41.2 dB3428997100
19LockedQAM25627591000000 Hz4.8 dBmV41.2 dB3429361600
20LockedQAM25628597000000 Hz4.5 dBmV41.2 dB3429737500
21LockedQAM25629603000000 Hz4.3 dBmV40.8 dB3430104600
22LockedQAM25630609000000 Hz3.9 dBmV40.7 dB3430494500
23LockedQAM25631615000000 Hz3.7 dBmV40.5 dB3430873500
24LockedQAM25632621000000 Hz3.8 dBmV40.6 dB3431209500
25LockedQAM25633627000000 Hz3.8 dBmV40.5 dB3431609800
26LockedQAM25634633000000 Hz3.8 dBmV40.3 dB3431993500
27LockedQAM25635639000000 Hz3.6 dBmV39.9 dB3432359000
28LockedQAM25636645000000 Hz3.4 dBmV39.8 dB3432699400
29LockedQAM25638657000000 Hz3.6 dBmV39.9 dB3433085200
30LockedQAM25639663000000 Hz3.8 dBmV40.1 dB3433207800
31LockedQAM25640669000000 Hz3.7 dBmV40.3 dB3433291300
32Not LockedUnknown00 Hz0.0 dBmV0.0 dB000

<tabindex=-1>Upstream Bonded Channels</tabindex=-1>

ChannelLock StatusModulationChannel IDFrequencyPower
1LockedATDMA135600000 Hz43.0 dBmV
2LockedATDMA229200000 Hz43.0 dBmV
3LockedATDMA322800000 Hz42.3 dBmV
4LockedATDMA416400000 Hz40.8 dBmV
5LockedATDMA940400000 Hz41.3 dBmV
6Not LockedUnknown00 Hz0.0 dBmV
7Not LockedUnknown00 Hz0.0 dBmV
8Not LockedUnknown00 Hz0.0 dBmV

<tabindex=-1>Downstream OFDM Channels</tabindex=-1>

ChannelLock StatusModulation / Profile IDChannel IDFrequencyPowerSNR / MERActive Subcarrier Number RangeUnerrored CodewordsCorrectable CodewordsUncorrectable Codewords
1Locked0, 1, 2, 341722000000 Hz4.5 dBmV39.3 dB1228 ~ 2867857347229285320
2Not Locked000 Hz4.8 dBmV0.0 dB0 ~ 4095000

<tabindex=-1>Upstream OFDMA Channels</tabindex=-1>

ChannelLock StatusModulation / Profile IDChannel IDFrequencyPower
1Not LockedUnknown00 Hz0 dBmV
2Not LockedUnknown00 Hz0 dBmV

Current System Time: Sun Oct 18 20:23:53 2020 System Up Time: 0:13:19

 

 

The event logs have the following issues

TimePriorityDescription
2020-10-18, 20:11:17Notice (6)DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=a0:04:60:fc:4f:50;CMTS-MAC=00:01:5c:b2:02:92;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedNotice (6)Honoring MDD; IP provisioning mode = IPv6
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=a0:04:60:fc:4f:50;CMTS-MAC=00:01:5c:b2:02:92;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=a0:04:60:fc:4f:50;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out;CM-MAC=a0:04:60:fc:4f:50;CMTS-MAC=00:01:5c:b2:02:92;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=a0:04:60:fc:4f:50;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not EstablishedCritical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=a0:04:60:fc:4f:50;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

 

Can someone help explain what the issue is with me not getting Gig speeds. I max out at 230 to 250 mpbs.

 

Please HELP.

 

Model: CM1000|Ultra-High Speed Cable Modem—DOCSIS® 3.1 Ready
Message 3 of 12
Gpai
Aspirant

Re: CM1000 not getting Gigabit speed with Xfinity

I tested directly hardwired through a laptop to my modem.

Model: CM1000|Ultra-High Speed Cable Modem—DOCSIS® 3.1 Ready
Message 4 of 12
FURRYe38
Guru

Re: CM1000 not getting Gigabit speed with Xfinity

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Be sure to power OFF the modem for 1 minute them back ON.

Factory reset the modem as well. 
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...

My Setup (Cable 1Gbps/50Mbps)>CAX80 v2.1.2.1(LAG Disabled)>RBK853 v3.2.18.223/SRK30 V3.2.33.106)
Additional NG HW: C7800/CM1100/CM1200CM2000, Orbi CBK40, RBK50, R7800, R7960P, EX7500/EX7700, XR450(v2.3.2.120) and WNHDE111
Message 5 of 12
Gpai
Aspirant

Re: CM1000 not getting Gigabit speed with Xfinity

Furrye38,

 

The ISP provider in this case Comcast came home yesterday and checked the quality of the signal coming inside the home. The was able to remove some issues with some interference and was able to demonstrate through his equipment that the signal was strong and he was gettting more than 1 gig connection for download.

 

And he connected the modem directly to the incoming RG6 Coax. While debugging by connecting my laptop directly to the modem ethernet out I also did the following

 

(a) I rebooted the modem several times and tried the connection

(b) Factory reset

(c) Each time waited a few mins (powered off, removed the coax connection, removed power input)

 

Both did not solve the issue.

 

I had asked the ISP to reprovision the modem before the Tech came in yesterday and that was not successful either. The only thing I have not done is to as them to reprovision after the tech came to visit. I will try that today and repost and see if it that makes a difference.

 

Would love for someone more knowledgeable than me to look at the settings I posted and logs and see if there is something they see glaring that I might be able to work with Comcast to fix.

 

Thanks again to everyone who is helping me resolve this !

Message 6 of 12
FURRYe38
Guru

Re: CM1000 not getting Gigabit speed with Xfinity

Seems like the ISP has checked everything. Seems like the the modem itself maybe the problem. I would get another modem put in place to see if the problem continutes...

My Setup (Cable 1Gbps/50Mbps)>CAX80 v2.1.2.1(LAG Disabled)>RBK853 v3.2.18.223/SRK30 V3.2.33.106)
Additional NG HW: C7800/CM1100/CM1200CM2000, Orbi CBK40, RBK50, R7800, R7960P, EX7500/EX7700, XR450(v2.3.2.120) and WNHDE111
Message 7 of 12
Gpai
Aspirant

Re: CM1000 not getting Gigabit speed with Xfinity

Do the logs indicate any issues?

 

Also I will see a reprovision helps from Comcast.

Message 8 of 12
FURRYe38
Guru

Re: CM1000 not getting Gigabit speed with Xfinity

I see some T3 time outs. 

This one user had similar time outs with there modem. Replaced it and now there up and running:

https://community.netgear.com/t5/Cable-Modems-Routers/How-to-confirm-C6300-hardware-issues/m-p/19931...

 

 

My Setup (Cable 1Gbps/50Mbps)>CAX80 v2.1.2.1(LAG Disabled)>RBK853 v3.2.18.223/SRK30 V3.2.33.106)
Additional NG HW: C7800/CM1100/CM1200CM2000, Orbi CBK40, RBK50, R7800, R7960P, EX7500/EX7700, XR450(v2.3.2.120) and WNHDE111
Message 9 of 12
Gpai
Aspirant

Re: CM1000 not getting Gigabit speed with Xfinity

Thanks for the post. Read the post indicated two issues

 

(a) T3 issues with line or modem (have to check)

(b) Issues with modem rebooting (that surely needed a modem replacement).

 

Helps me narrow it down. Thanks again for your help. I will see what my ISP says about T3 timeout issues.

Message 10 of 12
FURRYe38
Guru

Re: CM1000 not getting Gigabit speed with Xfinity

Lets us know how it goes...

My Setup (Cable 1Gbps/50Mbps)>CAX80 v2.1.2.1(LAG Disabled)>RBK853 v3.2.18.223/SRK30 V3.2.33.106)
Additional NG HW: C7800/CM1100/CM1200CM2000, Orbi CBK40, RBK50, R7800, R7960P, EX7500/EX7700, XR450(v2.3.2.120) and WNHDE111
Message 11 of 12
Gpai
Aspirant

Re: CM1000 not getting Gigabit speed with Xfinity

Here is what I found out more for T3 Timeouts.

T3 ( Ranging Request Retries Exhausted )

Explanation: The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also raise the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem’s power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process. This error message is DOCSIS event message is R03.0, Ranging Request.

T3 timeouts result when a Cable Modem, that is locked into the downstream, transmits a Ranging Request(RNG-REQ) to the CMTS(Cable Modem Termination System) and 200 milliseconds passes without the CM receiving a Ranging Response(RNG-RSP) from the CMTS. Indeed, maintaining a PING(Packet InterNet Groper) less than 200ms is important to a healthy DOCSIS network. When 10 T3s occur in succession (a period of 20 seconds passes without the CM receiving a Ranging Response, the CM will cease attempting to communicate with the HFC(Hybrid Fiber Optic Coaxial) network and reset its DOCSIS interface. In this case the RESET statistic on the modem log will increment but not all T3s will cause a reset if communication is restored within 10 T3 periods or 20 seconds. When T3 timeouts occur, but not enough occur in succession to trigger a reset, slow speeds are often a symptom as these timeouts slow down the TCP/IP handshakes necessary to maintain internet connections.

T3 Timeouts are typically caused by Upstream Noise causing Ranging Requests to not be clearly received by the CMTS. T3 problems can often be intermittant in nature as they may be the result of noise originating in any part of the plant that shares the same line card at the CMTS with the subscriber impacted. In fact, T3s can even be caused by noise originating on other neighboring nodes if resources are shared at the headend. Speed issues and intermittant connectivity issues are some of the most common problems encounted on our Trouble Calls.

T3 Timeouts can also be encountered when the plant's noise floor is so severe that the CM cannot overtalk it (SNR is bad and Noise power level is higher than your modem's signal). This can affect a single leg of the plant or even entire nodes. When a high noise floor results in several modems resetting their DOCSIS interface because 10 T3 timeouts have occured in succession, as we covered above, this is referred to as a noise outage. Noise outages frequently occur node-wide and while some may self-clear, many continue until a Plant Maintenence Technician locates and repairs the offending source of noise. This is why we ALL must be vigilant about preventing noise from entering the plant.

Occurrence: Extremely common in the customer homes

Symptom: Will cause intermittent disconnections. If you see couple of them, it is fine. If you quite a few of them consecutively, then it will lead to disconnections.

Example:
2017-6-14, 00:05:06 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=00:11:22:c1:db:09;CMTS-MAC=4c:00:82:ee:bd:62;CM-QOS=1.0;CM-VER=3.0

Fixes:
1. Check for the loose or Bad cables. This is by far most neglected and most common fix.
2. Remove extra splitters in house
3. Buy powered amplifier to boost your upstream power
4. Buy better coaxial cables
5. Call for a technician visit to inspect and fix cables outside and inside home (could be rain damage, fire damage, animal damage, construction damage, etc)

Message 12 of 12
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