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Star

Mar 28, 2019

Solved

CM1150V Upstream Channel Problem with Xfinity

I purchased a CM1150V to replace an Xfinity (Arris) XB6. The XB6 had been in place, running in bridge mode, for 2 months. It showed (4) upstream channels with good power levels, (31+OFDM) downstre...

Scott_UU
Apr 03, 2019
An Xfinity tech was out today. He found a noise block filter at the pole. No idea when or why it was installed. That was blocking the two lower frequency channels.

A noise block filter had previously been ruled out, because the Xfinity-supplied Arris XB6 was reporting all (4) channels locked. So I now question the veracity of the Arris XB6 status page. All other modems tested (CM1150V, Arris TM722G, Arris SBV3202) were unable to lock the channels with that filter in place. So I don't think the Arris XB6 was actually locking those channels either, even though it said it was.

Once the tech removed the noise block filter at the pole, the CM1150V immediately locked all (4) channels. The constant T3/T4 errors are gone as well. No problems with the CM1150V, the upstream issue was all from a previous Xfinity/Comcast tech installing that noise block filter at the tap.

Thanks to vkdelta for help and supporting information, which helped me explain/prove the problem to Xfinity so they would come fix it!

Scott_UU

Star

Apr 04, 2019

vkdelta wrote:

response>>

This is because of partial service on upstream. if you fix the coax/line/plant issues and all 4 upstreams are locked then LED will be solid.

But my upstream problem IS fixed... Channel status now shows all provisioned channels locked, and the "partial service" text is gone from the GUI. BUT THE LIGHT IS STILL FLASHING. Have tried power cycle and factory reset, US light still flashes. ????

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	29	663000000 Hz	-2.4 dBmV	38.8 dB	0	0
2	Locked	QAM256	1	483000000 Hz	-1.5 dBmV	39.8 dB	0	0
3	Locked	QAM256	2	489000000 Hz	-1.4 dBmV	39.8 dB	0	0
4	Locked	QAM256	3	495000000 Hz	-1.4 dBmV	39.8 dB	0	0
5	Locked	QAM256	4	507000000 Hz	-1.6 dBmV	39.7 dB	0	0
6	Locked	QAM256	5	513000000 Hz	-1.8 dBmV	39.7 dB	0	0
7	Locked	QAM256	6	519000000 Hz	-1.7 dBmV	39.8 dB	0	0
8	Locked	QAM256	7	525000000 Hz	-1.7 dBmV	39.8 dB	0	0
9	Locked	QAM256	8	531000000 Hz	-1.8 dBmV	39.7 dB	0	0
10	Locked	QAM256	9	543000000 Hz	-2 dBmV	39.6 dB	0	0
11	Locked	QAM256	10	549000000 Hz	-1.9 dBmV	39.6 dB	0	0
12	Locked	QAM256	11	555000000 Hz	-1.9 dBmV	39.5 dB	0	0
13	Locked	QAM256	12	561000000 Hz	-1.7 dBmV	39.6 dB	0	0
14	Locked	QAM256	13	567000000 Hz	-1.8 dBmV	39.6 dB	0	0
15	Locked	QAM256	14	573000000 Hz	-1.9 dBmV	39.6 dB	0	0
16	Locked	QAM256	15	579000000 Hz	-1.9 dBmV	39.5 dB	0	0
17	Locked	QAM256	16	585000000 Hz	-2 dBmV	39.5 dB	0	0
18	Locked	QAM256	17	591000000 Hz	-1.9 dBmV	39.5 dB	0	0
19	Locked	QAM256	18	597000000 Hz	-2 dBmV	39.4 dB	0	0
20	Locked	QAM256	19	603000000 Hz	-2.1 dBmV	39.3 dB	0	0
21	Locked	QAM256	20	609000000 Hz	-2.3 dBmV	39.3 dB	0	0
22	Locked	QAM256	21	615000000 Hz	-2.4 dBmV	39.2 dB	0	0
23	Locked	QAM256	22	621000000 Hz	-2.4 dBmV	39.1 dB	0	0
24	Locked	QAM256	23	627000000 Hz	-2.4 dBmV	39.1 dB	0	0
25	Locked	QAM256	24	633000000 Hz	-2.3 dBmV	39 dB	0	0
26	Locked	QAM256	25	639000000 Hz	-2.5 dBmV	38.9 dB	0	0
27	Locked	QAM256	26	645000000 Hz	-2.6 dBmV	38.8 dB	0	0
28	Locked	QAM256	27	651000000 Hz	-2.5 dBmV	38.7 dB	0	0
29	Locked	QAM256	28	657000000 Hz	-2.6 dBmV	38.8 dB	0	0
30	Locked	QAM256	30	669000000 Hz	-2.6 dBmV	38.7 dB	0	0
31	Locked	QAM256	31	675000000 Hz	-2.7 dBmV	37.9 dB	0	0
32	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	5	5120 Ksym/sec	30100000 Hz	39.3 dBmV
2	Locked	ATDMA	6	5120 Ksym/sec	36500000 Hz	39.8 dBmV
3	Locked	ATDMA	7	5120 Ksym/sec	17300000 Hz	37.3 dBmV
4	Locked	ATDMA	8	5120 Ksym/sec	23700000 Hz	38.3 dBmV
5	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
6	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV

Downstream OFDM Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power	SNR / MER	Active Subcarrier Number Range	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	0	159	722000000 Hz	-2.6 dBmV	38.0 dB	1126 ~ 2969	388467542	1	0
2	Not Locked	0	0	0 Hz	0 dBmV	0.0 dB	0 ~ 4095	0	0	0

Upstream OFDMA Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power
1	Not Locked	0	0	0 Hz	0 dBmV
2	Not Locked	0	0	0 Hz	0 dBmV

ChallD

Aspirant

Apr 24, 2019

I have the exact same problem.

FURRYe38
Guru - Experienced User
Apr 24, 2019
Contact the ISP and have them check the signal and channels for you. Possbile ask about a FW downgrade as well. The ISP should be able to fix this.

ChallD wrote:

I have the exact same problem.
Scott_UU
Star
Apr 24, 2019
ChallD wrote:

I have the exact same problem.

Good luck getting it resolved. I opened tickets with both Comcast and Netgear. Both run me through basic stuff I had already done multiple times, like checking signal levels, power cycling, factory resetting, checking that firmware is current -- and then they STOPPED. Neither will assign an engineer to actually look at details and interaction between modem/cmts to investigate and determine where the issue is; they instead just point fingers at each other to avoid any responsibility or real investigative work.

Comcast says everything is good at their end, all signal levels are great (both at modem and CMTS), correct firmware and provisioning file are in place, I'm getting provisioned speeds, and therefore it must be Netgear problem. Netgear dodges the question of the modem reporting both "full service" (via GUI) and "partial service" (via LED) at the same time, and just keeps telling me to talk to Comcast -- but Comcast has done everything Netgear asked, and the problem remains.

The CM1150V is contradicting itself, showing full service in GUI but partial service via the flashing LED. Both can't be right! So at a minimum, Netgear needs to fix their firmware to consistently report status via the GUI and LED. The ISP cannot do anything about that until Netgear gives them a new firmware to push out.
- FURRYe38
  Guru - Experienced User
  Apr 24, 2019
  You might try another same model cablemodem to see if the problem continues. Could be bad HW as well. Try a CM1100 modem and see if it does the same thing. If it does, then both NG and CC need to address this.
  - Scott_UU
    Star
    Apr 24, 2019
    FURRYe38 wrote:
    
    You might try another same model cablemodem to see if the problem continues. Could be bad HW as well. Try a CM1100 modem and see if it does the same thing.
    
    Already tried a second CM1150V, and it behaves the same. Also tried an Arris SBV3202 -- it does not indicate any service problems. That implies a CM1150V firmware problem, erroneously flashing the LED when no problem exists, but I don't have enough data to conclusively prove that. I'd use the Arris SBV3202, but it isn't Comcast-approved for future gigabit service which is why I went with the CM1150V -- but am keeping the SBV3202 as a backup / emergency spare. The CM1100 doesn't support voice, so that doesn't fit my needs. Having already purchased (3) modems and following extensive testing, logging, resets, etc. via tickets with both Netgear and Comcast, I feel like I've already gone further than any customer should have to go.
    
    FURRYe38 wrote:
    
    If it does, then both NG and CC need to address this.
    
    I agree, both Netgear and Comcast should be working together to isolate and correct whatever the problem is. Either the CM1150V is accurately detecting a partial service issue at Comcast and correctly flashing the Upstream LED (but failing to display that status in the GUI), *or* everything is just fine at Comcast and the CM1150V is erroneously flashing the LED.
    
    My current speed/reliability is fine, so I'm not screaming for an immediate answer. Just want to know that someone is working on it, and that it will eventually be addressed. Obviously something is wrong, with either the service or the status reporting, and it would be nice to know that someone cares about fixing that problem even if speed/reliability isn't impacted.