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CM3000 Cable Modem Upload Stream Issues
I have had Cox communications to my house several times in the past month and a half. They've replaced all the cable connections both in and out of my house. I have 2 gig download 100+MBPS upload. The download is fine, the upload will not go past 40 MBPS no matter what we try. He checked the speed without using the modem and he was getting 113 mbps uploads. Once connected to the cable modem, 39-40 if I'm lucky. This modem is less than 5 months old. I can't see any settings in the UI to adjust. Keep in mind this was working fine until recently.CM3000
I purchased a used CM3000 back in June from eBay. It has worked great for the last three months with my TP-Link Archer GE800 router. I just moved and had my Xfinity service transferred to my new address, setting everything up and activating it. However, for some reason, the modem's multi-gig light turns off whenever I use the Wi-Fi from my router. If I am hard-wired, it doesn't have an issue. Still, I have watched the modem's multi-gig light turn off and cause the router to lose connection as soon as I launch anything on my phone that requires Wi-Fi, for example, I have launched the speedtest by Ookla app, and I run a speedtest and instantly watch the speed jump, and then go to zero because the multi-gig light turns off. I work for Xfinity as a technician, so I have verified signal levels and confirmed that everything on the ISP side is functioning correctly. Has anyone else encountered or seen this issue?CM3000 Repeated Cox disconnects with SYNC Timing Synchronization failure
The CM3000, which I have owned for <30 days, is having repeated disconnection issues. Cox is my ISP. The disconnections occur randomly, but multiple times per day and always require a hard reboot. The Event Log shows many lines associated with each disconnect, but the "critical" error that prompts the disconnect appears to be the following: SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=54:07:7d:c6:e4:28;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1; This identical entry has occurred dozens of times. Cox technicians have replaced all cable lines and connections to and from the modem out to the street. The last Cox service technician says that the modem is failing to maintain an upstream channel lock and that the problem is with the modem. Additional information: Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 5 141000000 Hz 7.9 dBmV 45.6 dB 0 0 2 Locked QAM256 1 117000000 Hz 7.6 dBmV 45.2 dB 0 0 3 Locked QAM256 2 123000000 Hz 7.9 dBmV 45.6 dB 0 0 4 Locked QAM256 3 129000000 Hz 7.9 dBmV 45.6 dB 0 0 5 Locked QAM256 4 135000000 Hz 8.0 dBmV 45.8 dB 0 0 6 Locked QAM256 6 147000000 Hz 7.8 dBmV 45.9 dB 0 0 7 Locked QAM256 7 153000000 Hz 7.7 dBmV 45.9 dB 0 0 8 Locked QAM256 8 159000000 Hz 7.7 dBmV 45.9 dB 0 0 9 Locked QAM256 9 165000000 Hz 7.6 dBmV 45.9 dB 0 0 10 Locked QAM256 10 171000000 Hz 7.6 dBmV 46.0 dB 0 0 11 Locked QAM256 11 177000000 Hz 7.5 dBmV 45.9 dB 0 0 12 Locked QAM256 12 183000000 Hz 7.7 dBmV 46.0 dB 0 0 13 Locked QAM256 13 189000000 Hz 7.7 dBmV 46.0 dB 0 0 14 Locked QAM256 14 195000000 Hz 7.8 dBmV 44.5 dB 0 0 15 Locked QAM256 15 201000000 Hz 7.8 dBmV 45.1 dB 0 0 16 Locked QAM256 16 207000000 Hz 7.8 dBmV 45.3 dB 0 0 17 Locked QAM256 17 213000000 Hz 7.9 dBmV 46.0 dB 0 0 18 Locked QAM256 18 219000000 Hz 7.8 dBmV 46.1 dB 0 0 19 Locked QAM256 19 225000000 Hz 7.7 dBmV 46.2 dB 0 0 20 Locked QAM256 20 231000000 Hz 7.7 dBmV 46.3 dB 0 0 21 Locked QAM256 21 237000000 Hz 7.5 dBmV 46.3 dB 0 0 22 Locked QAM256 22 243000000 Hz 7.5 dBmV 46.3 dB 0 0 23 Locked QAM256 23 249000000 Hz 7.4 dBmV 46.3 dB 0 0 24 Locked QAM256 24 255000000 Hz 7.4 dBmV 46.0 dB 0 0 25 Locked QAM256 25 735000000 Hz 6.0 dBmV 44.1 dB 0 0 26 Locked QAM256 26 741000000 Hz 6.0 dBmV 44.0 dB 0 0 27 Locked QAM256 27 747000000 Hz 5.9 dBmV 43.9 dB 0 0 28 Locked QAM256 28 753000000 Hz 6.2 dBmV 43.9 dB 0 0 29 Locked QAM256 29 759000000 Hz 6.1 dBmV 43.8 dB 0 0 30 Locked QAM256 30 765000000 Hz 6.0 dBmV 43.8 dB 0 0 31 Locked QAM256 31 771000000 Hz 5.9 dBmV 43.7 dB 0 0 32 Locked QAM256 32 777000000 Hz 5.7 dBmV 43.6 dB 0 0 Upstream Bonded Channels (Partial Service) Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power 1 Locked ATDMA 2 5120 Ksym/sec 24000000 Hz 34.5 dBmV 2 Locked ATDMA 1 5120 Ksym/sec 17600000 Hz 34.0 dBmV 3 Locked ATDMA 3 5120 Ksym/sec 30400000 Hz 34.5 dBmV 4 Locked ATDMA 4 5120 Ksym/sec 36800000 Hz 35.0 dBmV 5 Not Locked Unknown 0 0 0 0.0 dBmV 6 Not Locked Unknown 0 0 0 0.0 dBmV 7 Not Locked Unknown 0 0 0 0.0 dBmV 8 Not Locked Unknown 0 0 0 0.0 dBmV Downstream OFDM Channels Channel Lock Status Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier Number Range Unerrored Codewords Correctable Codewords Uncorrectable Codewords 1 Locked 0 ,1 ,2 ,3 159 300000000 Hz 7.78 dBmV 45.5 dB 296 ~ 7895 82294164 17164821 0 2 Locked 0 ,1 ,2 ,3 160 918000000 Hz 7.18 dBmV 43.4 dB 2216 ~ 5975 82167677 11066105 34 Upstream OFDMA Channels Channel Lock Status Modulation / Profile ID Channel ID Frequency Power 1 Not Locked 11 ,13 6 36800000 Hz 31.0 dBmV 2 Not Locked 0 0 0 Hz 0 dBmV Advice, assistance would be much appreciated.Spectrum CM3000
Just wanted to provide an update. I don't know what changed because it's still showing firmware version V6.01.03 but as of today the CM3000 seems to have stabilized and appears to be working normally again on Spectrum. That being said I CAN'T vouch if the same is true for any other service provider.I had the same issue a while back and they (comcast)
Hello. I know this is pretty old but did you ever get it figured out? I had the same issue a while back and they (comcast) ended up having to replace the cable from my house to the tap. They ended up having to send three different techs before they replaced the line. it was super frustrating.My downstream LED went out a few days ago but the CM3000 is fully functional
I as well have the Xfinity Gigabit X2 plan. My downstream LED went out a few days ago but the CM3000 is fully functional and all 32 downstream channels are locked. I installed this modem on 1/15/2025 and has been working fine for 6 Months. However, a few weeks ago my online LED went out and a few weeks later it came back on and now only the Downstream is out. I don't know what is going on. One would think if a LED is burnt out it would never come back on ever.Nighthawk CM3000, FW 6 .01.03 randomly disconnects from internet
I have been working with Xfinity for a month now, had my cable wiring replaced inside the house to the modem, had the wiring inspected outside the house, still have random disconnects. Xfinity says everything is great on their end... trying to get ahold of Netgear but am outside of my 90 day window... purchased the modem last November... requesting a replacement. Any help for this issue? Am attaching a copy of the event log.CM3000 Comcast Business Slow Upload
Using the Comcast provided modem I get > 300 Mbps upload. Changing to the CM3000 I get 30. I've spent hours with Comcast tech support and had multiple technicians out. Thoughts? Cable Diagnostic Status: Good Action: Your setup looks fine. If you can't access the internet, make sure you properly activated the modem. If modem has been activated and you still can't access the internet, contact your service provider for troubleshooting help. If you can access the internet but has other internet issue, the Netgear Cable Knowledge Base can provide additional troubleshooting info. CM Status: Good Downstream Status: Good Downstream Power Level: Good Downstream SNR Level: Good Upstream Status: Good Upstream Power Level: Good Current Time: Wed Jun 18 10:14:04 2025 Startup Procedure Acquire Downstream Channel: 495000000 Hz Locked Connectivity State: OK Operational Boot State: OK Operational Security: Enabled BPI+ IP Provisioning Mode: Honor MDD IPv6 only Downstream Bonded Channels Channel LockedStatus Modulation ChannelID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 12 495000000 Hz 4.5 44.4 0 0 2 Locked QAM256 1 429000000 Hz 5.4 45 0 0 3 Locked QAM256 2 435000000 Hz 5.4 45 0 0 4 Locked QAM256 3 441000000 Hz 5.2 44.9 0 0 5 Locked QAM256 4 447000000 Hz 5.2 44.8 0 0 6 Locked QAM256 5 453000000 Hz 5.2 44.8 0 0 7 Locked QAM256 6 459000000 Hz 5 44.7 0 0 8 Locked QAM256 7 465000000 Hz 4.9 44.6 0 0 9 Locked QAM256 8 471000000 Hz 4.8 44.5 0 0 10 Locked QAM256 9 477000000 Hz 4.8 44.5 0 0 11 Locked QAM256 10 483000000 Hz 4.6 44.4 0 0 12 Locked QAM256 11 489000000 Hz 4.6 44.4 0 0 13 Locked QAM256 13 501000000 Hz 4.5 44.3 0 0 14 Locked QAM256 14 507000000 Hz 4.4 44.3 0 0 15 Locked QAM256 15 513000000 Hz 4.2 44.1 0 0 16 Locked QAM256 16 519000000 Hz 4.1 44.1 0 0 17 Locked QAM256 17 525000000 Hz 4.2 44.1 0 0 18 Locked QAM256 18 531000000 Hz 4.3 44.2 0 0 19 Locked QAM256 19 537000000 Hz 4 44 0 0 20 Locked QAM256 20 543000000 Hz 4.1 44 0 0 21 Locked QAM256 21 549000000 Hz 4 43.9 0 0 22 Locked QAM256 22 555000000 Hz 4 43.9 0 0 23 Locked QAM256 23 561000000 Hz 4.1 43.9 0 0 24 Locked QAM256 24 567000000 Hz 4 43.9 0 0 25 Locked QAM256 25 573000000 Hz 4.1 43.9 0 0 26 Locked QAM256 26 579000000 Hz 4.1 43.8 0 0 27 Locked QAM256 27 585000000 Hz 3.9 43.7 0 0 28 Locked QAM256 28 591000000 Hz 4.1 43.8 0 0 29 Locked QAM256 29 597000000 Hz 4.1 43.8 0 0 30 Locked QAM256 30 603000000 Hz 3.9 43.7 0 0 31 Locked QAM256 31 609000000 Hz 4 43.8 0 0 32 Locked QAM256 32 615000000 Hz 3.9 43.7 0 0 Upstream Bonded Channels Channel LockedStatus ChannelType ChannelID SymbolRate Frequency Power 1 Locked ATDMA 18 5120 Ksym/sec 22800000 Hz 38.3 dBmV 2 Locked ATDMA 19 5120 Ksym/sec 29200000 Hz 39.3 dBmV 3 Locked ATDMA 20 5120 Ksym/sec 35600000 Hz 40.3 dBmV 4 Locked ATDMA 17 5120 Ksym/sec 16400000 Hz 37.5 dBmV 5 Not Locked Unknown 0 0 0 0.0 6 Not Locked Unknown 0 0 0 0.0 7 Not Locked Unknown 0 0 0 0.0 8 Not Locked Unknown 0 0 0 0.0 Downstream OFDM Channels Channel LockedStatus ProfileID ChannelID Frequency Power SNR/MER ActiveSubcarrier Unerror Correctable Uncorrectable 1 Locked 0 ,1 ,2 ,3 193 957000000 Hz 1.58 dBmV 41.4 dB 148 ~ 3947 6699720 5862969 0 2 Not Locked 0 0 0 Hz 0 dBmV 0 dB 0 ~ 4095 0 0 0 Upstream OFDMA Channels Channel LockedStatus ProfileID ChannelID Frequency Power 1 Locked 12 ,13 43 36200000 Hz 35.5 dBmV 2 Not Locked 0 0 0 Hz 0 dBmV
