CM1000 Xfinity issues

[Nicholas_]

I'm getting lag and slow download speed on games

[kingtj]

You didn't give nearly enough information for people here to help you troubleshoot. But for what it's worth? I ran into your post while looking for discussions about Netgear CM1000 and CM1150v modems having problems getting the speed Comcast customers are paying for.

I purchased a CM1000 initially and had problems where it was only getting about 400mbits/sec top speeds despite having the gigabit tier of service from Comcast/XFinity.  I switched to the CM1150v since I also have Comcast voice service and realized that modem was essentially a CM1000 with phone jacks on it too, for their voice service.

Same problem though....  Modem can't get over about half the speed I'm paying for, even with a laptop plugged right in the back of it over wired Ethernet that defiinitely can handle 1 gigabit speed.

I still have the XB6 Comcast Xfi gateway they provided when I signed up for gigabit service, and when I set it up instead of the Netgear, I get the speeds I'm supposed to get. A Comcast tech came out and confirmed my line conditions are "excellent", as well -- and couldn't explain why the Netgear modem was so much slower.

I see several other message threads here with the same basic problem, although in at least 1 or 2 situations, it looks like at least PART of the problem was poor signal quality from Comcast.  Still, I've done all the troubleshooting steps and know my circuit works reliably at gigabit speed when using the XB6.  Comcast insists my Netgear modem was properly provisioned, and the tech even called in to verify that with a level 3 person.  I'm about to give up and return this modem, and just resign myself to paying Comcast the stupid monthly modem rental fee -- at least until another product comes out that works better with their system.

[JJNorcal]

@kingtj, did you make any further progress with your CM1150v?

I'm in pretty much the same place you were.  I'm getting mid 500mbps.  While I have never seen my laptop attain gig speeds, it is a one year old high end spectre x360, and all available specs indicating I should be good.

I worked with Netgear support once.  They pointed to their specs indicating that power should be between -7 and +7 db.  I was at 10+.  Comcast attenuated and I'm now between 5 and 6.8.

I believe this did improve the speed somewhat, taking me up to mid to high 500s.

I'm very interested in the end of your story.

Thanks!

[jdmoto]

I feel like I'm on the same boat as you guys. I recently updated Xifitnty Gig service and purcashed a CM1100 to handle the new speed, but so far I'm only getting half the speed downstream (500-600mbps) and full upstream speed (40mbps).  I've factory reset the modem and Orbi router once, still getting the same issue. Is there a way to check the boot/config file? 

I have a tech coming in tomorrow morning to check the line, but i have a feeling the line will not be an issue. 

[JJNorcal]

@jdmoto , just now seeing this.  Netgear suggested I return my modem and get a replacement.  This did not NOT result in better speeds.

I believe I ran into @kingtj's outcome in another thread.  I think he returned his modem, as he was definitively able to get gig speeds with another Comcast modem.

I picked up an xFi and local Comcast store, but it did NOT improve my speeds.  In fact, slightly slower than my CM1150v.

I'm not sure what I'm going to do next.  How did your tech visit go, and did you find finally attain expected speeds?

[jdmoto]

@JJNorcal, during the tech visit the tech reloaded the firmware into the cm1100. After the update and reboot I was able to obtain the gig speed. 950/40 but only to certain servers. I'm guess this is due to server limits and distance. My connection to Xfinity servers is gig speed.

I'm sorry to hear that your still having trouble...

[jrowlands]

I have the Netgear CM1150v Docsis 3.1 cable modem telephony and am curious about the downstream channels. Channel 32 is not locked on. Channels 1-31 are locked on, but I do not see any of the Docsis 3.1 frequencies allocated to the modem. I was told the Docsis 3.1 frequencies are above 677Mhz. My frequencies are 477-677. I am experiencing erratic download speeds while the upload speeds are somewhat consistent ranging between 32-41mbps. Downloads range from 647mbps down to 25mbps. Powering the modem, re-provision from xfinity, multiple technician visits, and so on. Any help?

[Nicholas_]

I haven't been able to fix it. I've been working alot sorry for the late respons. I'm having alot of issue with netgear and comcast.

Time Priority Description 2019-03-02, 11:12:59 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; 2019-03-01, 17:40:38 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 .;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6 Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; 2019-02-24, 15:35:06 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:01:5c:70:04:5c;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=78:d2:94:5b:02:f8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Help Center S

[Nicholas_]

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 657000000
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 657000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enable BPI+
IP Provisioning Mode Honor MDD IPv6 only
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked QAM256 33 657000000 Hz 12.2 dBmV 42.4 dB 2628219619 27 162
2 Locked QAM256 2 471000000 Hz 10.0 dBmV 42.3 dB 2627690026 0 0
3 Locked QAM256 3 477000000 Hz 10.1 dBmV 42.3 dB 2627694289 0 0
4 Locked QAM256 4 483000000 Hz 10.3 dBmV 42.6 dB 2627698643 0 0
5 Locked QAM256 5 489000000 Hz 10.3 dBmV 42.4 dB 2627702265 0 0
6 Locked QAM256 6 495000000 Hz 10.3 dBmV 42.3 dB 2627707298 0 0
7 Locked QAM256 7 507000000 Hz 10.4 dBmV 42.4 dB 2627710114 0 0
8 Locked QAM256 8 513000000 Hz 10.3 dBmV 42.3 dB 2627712397 0 0
9 Locked QAM256 9 519000000 Hz 10.5 dBmV 41.9 dB 2627745354 0 0
10 Locked QAM256 10 525000000 Hz 10.6 dBmV 42.7 dB 2627749207 0 0
11 Locked QAM256 11 531000000 Hz 10.7 dBmV 42.5 dB 2627753273 0 0
12 Locked QAM256 12 537000000 Hz 10.9 dBmV 42.7 dB 2627757313 0 0
13 Locked QAM256 13 543000000 Hz 10.8 dBmV 42.4 dB 2627760598 0 0
14 Locked QAM256 14 549000000 Hz 10.6 dBmV 42.4 dB 2627764603 0 0
15 Locked QAM256 15 555000000 Hz 10.8 dBmV 42.3 dB 2627767999 0 0
16 Locked QAM256 16 561000000 Hz 10.9 dBmV 42.4 dB 2627771069 0 0
17 Locked QAM256 17 567000000 Hz 10.9 dBmV 42.4 dB 2627820563 0 0
18 Locked QAM256 18 573000000 Hz 11.3 dBmV 42.5 dB 2627824749 0 0
19 Locked QAM256 19 579000000 Hz 11.2 dBmV 42.3 dB 2627828061 0 0
20 Locked QAM256 20 585000000 Hz 11.3 dBmV 42.1 dB 2627831918 0 0
21 Locked QAM256 21 591000000 Hz 11.4 dBmV 42.3 dB 2627835964 0 0
22 Locked QAM256 22 597000000 Hz 11.3 dBmV 42.3 dB 2627839413 0 0
23 Locked QAM256 23 603000000 Hz 11.1 dBmV 42.2 dB 2627843172 0 0
24 Locked QAM256 24 609000000 Hz 11.1 dBmV 42.4 dB 2627847188 0 0
25 Locked QAM256 25 615000000 Hz 11.1 dBmV 42.1 dB 2627850691 0 0
26 Locked QAM256 26 621000000 Hz 11.1 dBmV 42.2 dB 2627854084 0 0
27 Locked QAM256 27 627000000 Hz 11.1 dBmV 42.1 dB 2627862833 0 0
28 Locked QAM256 28 633000000 Hz 11.3 dBmV 41.9 dB 2627862293 0 0
29 Locked QAM256 30 639000000 Hz 11.5 dBmV 41.8 dB 2627836665 0 0
30 Locked QAM256 31 645000000 Hz 11.9 dBmV 42.4 dB 2627839118 0 0
31 Locked QAM256 32 651000000 Hz 11.9 dBmV 42.2 dB 2627841380 0 0
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 0
Upstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power
1 Locked ATDMA 1 35800000 Hz 38.5 dBmV
2 Locked ATDMA 2 29400000 Hz 38.8 dBmV
3 Locked ATDMA 3 23000000 Hz 38.5 dBmV
4 Locked ATDMA 4 16600000 Hz 39.0 dBmV
5 Not Locked Unknown 0 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 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, 1, 255 29 690000000 Hz 12.8 dBmV 41.0 dB 1108 ~ 2987 766799633 441709643 0
2 Not Locked 0, 255 0 0 Hz 5.3 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 Unknown 0 0 Hz 0 dBmV
2 Not Locked Unknown 0 0 Hz 0 dBmV