I'm experiencing slow upload speeds with my CM1000 cable modem on Comcast's network. My plan is for 300Mbps down, 25Mbps upstream. The download speed is close to 300, but the upload speed ranges from 2-8 on various speed test websites. This is a new issue that started happening in some time in the past few weeks. Comcast's support has told me everything looks good on their end, and since this is not their modem they said I have to contact Netgear for further support. Is anyone able to help with my issue? Thanks.

power levels look good. have you had better US speeds before?Please PM me you CM MAC, CMTS MAC, and location of the device (city, state).

I believe so. The reason this came to my attention is that I'm sharing videos via Plex with a friend. Before this worked without issue, but now we are getting major buffering issues. I think 8 Mbps up would not cause buffering issues for the size/quality of the videos I am sharing, but it appears my real upload speed is closer to 2 Mbps according to testmy.net (and others) -- this speed could be the source of our buffering issues, and at any rate I would expect to get upload speeds much closer to my provisioned speed of 25. I will PM you those details.

Hello, I have this same Modem with Xfinity and got that same event log about the DS profile change. I have also been gettng T3 timeouts with slow loading pages and had to quit using IE11 completely because of speed issues. Some of my regular speed test slow down at the end of the download test and then timeout on the upload side. I was wonering if this had been solved for you yet? For me this all started around a week ago. Xfinity even replaced my outside cabling but the issue still persist.

Slow Upload Speeds on CM1000 | NETGEAR Communities

14 Replies

vkdelta

NETGEAR Employee Retired

Oct 02, 2017

which website did you check?

what speeds do you see on the COMCAST speedtest website?

please post your power levels and event logs.

tylert

Aspirant

Oct 02, 2017

I've used various sites including speedtest.xfinity.com. On Comcast's site I get 8 Mbps up. For most other sites, I get a lower value, including for testmy.net I get 1-2 Mbps up.

Here are some diagnostics:

Startup Procedure
Procedure	Status	Comment
Acquire Downstream Channel	501000000 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	1	501000000 Hz	-4.3 dBmV	34.8 dB	1757896329	2	0
2	Locked	QAM256	2	507000000 Hz	-4.1 dBmV	35.2 dB	1757981574	7	0
3	Locked	QAM256	3	513000000 Hz	-4.4 dBmV	36.8 dB	1757991529	2	0
4	Locked	QAM256	4	519000000 Hz	-4.1 dBmV	37.9 dB	1758000571	3	0
5	Locked	QAM256	5	525000000 Hz	-4.3 dBmV	38.2 dB	1757996771	2	0
6	Locked	QAM256	6	531000000 Hz	-4.2 dBmV	38.2 dB	1758019361	1	0
7	Locked	QAM256	7	537000000 Hz	-3.8 dBmV	35.9 dB	1758028180	7	0
8	Locked	QAM256	8	543000000 Hz	-4.1 dBmV	37.6 dB	1758037685	1	0
9	Locked	QAM256	9	555000000 Hz	-4.1 dBmV	36.6 dB	1758053097	0	0
10	Locked	QAM256	10	561000000 Hz	-4.6 dBmV	38.0 dB	1758062473	0	0
11	Locked	QAM256	11	567000000 Hz	-4.1 dBmV	38.2 dB	1758072040	1	0
12	Locked	QAM256	12	573000000 Hz	-4.2 dBmV	38.2 dB	1758080995	1	0
13	Locked	QAM256	13	579000000 Hz	-4.7 dBmV	38.1 dB	1758090912	1	0
14	Locked	QAM256	14	585000000 Hz	-4.6 dBmV	38.0 dB	1758099878	1	0
15	Locked	QAM256	15	591000000 Hz	-5.1 dBmV	38.0 dB	1758109215	5	0
16	Locked	QAM256	16	597000000 Hz	-4.7 dBmV	38.0 dB	1758118694	1	0
17	Locked	QAM256	17	603000000 Hz	-4.5 dBmV	38.0 dB	1758144398	7	0
18	Locked	QAM256	18	609000000 Hz	-4.7 dBmV	38.0 dB	1758153128	2	0
19	Locked	QAM256	19	615000000 Hz	-4.4 dBmV	38.0 dB	1758134012	0	0
20	Locked	QAM256	20	621000000 Hz	-4.4 dBmV	29.9 dB	1758064993	106959	21
21	Locked	QAM256	21	627000000 Hz	-5.0 dBmV	33.3 dB	1758180416	28	0
22	Locked	QAM256	22	633000000 Hz	-4.6 dBmV	37.9 dB	1758185578	0	0
23	Locked	QAM256	23	639000000 Hz	-5.0 dBmV	37.9 dB	1758199258	7	0
24	Locked	QAM256	24	645000000 Hz	-5.1 dBmV	37.1 dB	1758208851	5	0
25	Locked	QAM256	26	651000000 Hz	-5.1 dBmV	36.1 dB	1758234773	0	0
26	Locked	QAM256	27	657000000 Hz	-5.9 dBmV	36.8 dB	1758242943	3	0
27	Locked	QAM256	28	663000000 Hz	-5.0 dBmV	37.8 dB	1758249000	6	0
28	Locked	QAM256	29	669000000 Hz	-5.2 dBmV	38.0 dB	1758255529	8	0
29	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
30	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
31	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	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	73	35600000 Hz	46.8 dBmV
2	Locked	ATDMA	74	29200000 Hz	47.3 dBmV
3	Locked	ATDMA	75	22800000 Hz	47.3 dBmV
4	Locked	ATDMA	76	16000000 Hz	46.8 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	25	720000000 Hz	-5.6 dBmV	27.5 dB	1108 ~ 2987	81678594	25215901	0
2	Not Locked	0	0	0 Hz	-5.1 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

Here is my event log, taken from 10/2 at 10:40 AM EST -- I've masked the MAC addresses:

 Time	Priority	Description
2017-10-01, 22:50:10	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=a0:04:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
2017-10-01, 22:50:07	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 .;CM-MAC=a0:04:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=a0:04:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;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=a0:04:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2017-10-01, 22:34:44	Critical (3)	Resetting the cable modem due to docsDevResetNow
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=a0:04:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;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=a0:04:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2017-10-01, 22:31:01	Critical (3)	Resetting the cable modem due to docsDevResetNow
2017-10-01, 22:26:02	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=a0:04:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;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=a0:04:xx:xx:xx:xx;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=a0:04:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;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=a0:04:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

vkdelta
NETGEAR Employee Retired
Oct 02, 2017
power levels look good.

have you had better US speeds before?
Please PM me you CM MAC, CMTS MAC, and location of the device (city, state).

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Slow Upload Speeds on CM1000