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Forum Discussion
Netgear CM2000 modem keeps dropping internet speed from 100 to 10 MBPS
Device: Nighthaw CM2000 modem
Firmware: V1.01.08
Service: Comcast Xfinity 100Mbps cable internet
Problem: Speed drops from around 100 to 10 or below randomly throughout the day.
Hey all, I moved to a new place and am having a problem with my internet.
What I did so far:
1. I have plugged directly into the modem and experienced it so it's not the wifi.
2. Often it helps to reset my router
3. I asked comcast to come by
-the guy went up the pole and into my house and
-he disconnected a couple of cables just in case they were causing interference and replaced something he said but nothing big
-he said there wasn't anything he could see causing it, the downstream was consistent, and occasionally the upstream looked jittery but that shouldn't be causing it (he put a ticket in with someone to look at the line and ensure nothing was wrong with it).
Any advice you can give? I make my living by making video calls so this is hurting me quite a bit.
I looked at the modem logs but don't know how to interpret them (I only hid the MAC addresses with the "x"):
| Tue Nov 09 08:48:55 2021 | (Critical (3)) | SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; |
| Tue Nov 09 08:48:55 2021 | (Notice (6)) | DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1; |
| Tue Nov 09 08:48:50 2021 | (Notice (6)) | TLV-11 - unrecognized OID;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx: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=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx: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=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; |
2 Replies
I see some other data in the logs as well:
Startup Procedure Procedure Status Comment Acquire Downstream Channel 507000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Security Enabled BPI+ Downstream Bonded Channels Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 20 507000000 Hz 4.7 dBmV 40.7 dB 0 0 2 Locked QAM256 17 483000000 Hz 4.5 dBmV 40.7 dB 0 0 3 Locked QAM256 18 489000000 Hz 4.6 dBmV 40.6 dB 0 0 4 Locked QAM256 19 495000000 Hz 4.6 dBmV 40.7 dB 0 0 5 Locked QAM256 21 513000000 Hz 4.7 dBmV 40.8 dB 0 0 6 Locked QAM256 22 519000000 Hz 4.8 dBmV 40.8 dB 0 0 7 Locked QAM256 23 525000000 Hz 5.0 dBmV 40.8 dB 0 0 8 Locked QAM256 24 531000000 Hz 5.1 dBmV 40.9 dB 0 0 9 Locked QAM256 25 543000000 Hz 5.0 dBmV 40.8 dB 0 0 10 Locked QAM256 26 549000000 Hz 4.9 dBmV 40.8 dB 0 0 11 Locked QAM256 27 555000000 Hz 4.8 dBmV 40.9 dB 0 0 12 Locked QAM256 28 561000000 Hz 4.7 dBmV 40.9 dB 0 0 13 Locked QAM256 29 567000000 Hz 4.4 dBmV 40.7 dB 0 0 14 Locked QAM256 30 573000000 Hz 3.7 dBmV 40.4 dB 0 0 15 Locked QAM256 31 579000000 Hz 2.7 dBmV 40.0 dB 0 0 16 Locked QAM256 32 585000000 Hz 1.9 dBmV 39.6 dB 0 0 17 Locked QAM256 33 591000000 Hz 1.8 dBmV 39.8 dB 0 0 18 Locked QAM256 34 597000000 Hz 3.0 dBmV 40.2 dB 0 0 19 Locked QAM256 35 603000000 Hz 3.9 dBmV 40.5 dB 0 0 20 Locked QAM256 36 609000000 Hz 4.8 dBmV 40.8 dB 0 0 21 Locked QAM256 37 615000000 Hz 5.3 dBmV 40.9 dB 0 0 22 Locked QAM256 38 621000000 Hz 5.3 dBmV 40.9 dB 0 0 23 Locked QAM256 39 627000000 Hz 5.4 dBmV 40.9 dB 0 0 24 Locked QAM256 40 633000000 Hz 5.7 dBmV 40.9 dB 0 0 25 Locked QAM256 41 639000000 Hz 5.9 dBmV 40.9 dB 0 0 26 Locked QAM256 42 645000000 Hz 6.3 dBmV 41.1 dB 0 0 27 Locked QAM256 43 651000000 Hz 6.3 dBmV 40.9 dB 0 0 28 Locked QAM256 44 657000000 Hz 6.5 dBmV 41.0 dB 0 0 29 Locked QAM256 45 663000000 Hz 6.8 dBmV 41.1 dB 0 0 30 Locked QAM256 46 669000000 Hz 7.3 dBmV 41.2 dB 0 0 31 Locked QAM256 47 675000000 Hz 6.8 dBmV 40.8 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 1 5120 16400000 Hz 45.3 dBmV 2 Locked ATDMA 2 5120 22800000 Hz 46.3 dBmV 3 Locked ATDMA 3 5120 29200000 Hz 46.3 dBmV 4 Locked ATDMA 4 5120 35600000 Hz 46.8 dBmV 5 Locked ATDMA 5 1280 39600000 Hz 43.5 dBmV 6 Not Locked Unknown 0 0 0 Hz 0.0 dBmV 7 Not Locked Unknown 0 0 0 Hz 0.0 dBmV 8 Not Locked Unknown 0 0 0 Hz 0.0 dBmV Downstream OFDM Channels Channel Lock
StatusModulation /
Profile IDChannel
IDFrequency Power SNR /
MERActive Subcarrier
Number RangeUnerrored
CodewordsCorrectable
CodewordsUncorrectable
Codewords1 Locked 0 ,1 ,2 ,3 48 688000000 Hz 6.8 dBmV 40.5 dB 1108 ~ 2987 7338633 7031821 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 Use if for a bit and then re-run the logs. It looks like it was just ran. A bit longer period is needed. The cable connections page just shows when it was ran versus the log shows us a longer runtime.
