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Forum Discussion
CM1100 dropping connections
Comcast technician says their diagnostics is fine from their end, but my connection drops several times in a day. 1. Trying to understand these errors so that I can have better coversation with C...
i bought my unit from costco about 2 months ago and i have this issue where after about 2 weeks my cox internet goes down. when it first started happening it would come back in 15 minutes then it would go down a couple days later but then come back up in 30 minutes. i just assumed it was Cox. after a few times this happened and after somteims wairing 1-2 hours for it to come back online, i finally called Cox and they said that the cable modem was offline and to reboot it.
so i powercycled it, voila it started working a couple weeks ago. now it happened again yesterday and i powercycle it, and then it starts to work again.
seems like something is off with the modem. i logged into it yesterday to check the logs and it had some entries about DHCP error like it couldnt grab DHCP for some reason.
Have the ISP check the signal and line quality UP to the modem.
Be sure there are no coax cable line splitters in the between the modem and ISP service box.
Be sure your using good quality RG6 coax cable up to the modem.
itsjohnchow wrote:i bought my unit from costco about 2 months ago and i have this issue where after about 2 weeks my cox internet goes down. when it first started happening it would come back in 15 minutes then it would go down a couple days later but then come back up in 30 minutes. i just assumed it was Cox. after a few times this happened and after somteims wairing 1-2 hours for it to come back online, i finally called Cox and they said that the cable modem was offline and to reboot it.
so i powercycled it, voila it started working a couple weeks ago. now it happened again yesterday and i powercycle it, and then it starts to work again.
seems like something is off with the modem. i logged into it yesterday to check the logs and it had some entries about DHCP error like it couldnt grab DHCP for some reason.
My issue was intermittent signal problems from the ISP. They had to come out to diagnose the problem. From their internal technicians side it just looked like the modem was periodically rebooting. After a lot of troubleshooting... new modems... and other things... finally got back to the original configuration and they agreed to come out - solving it roughly a day later after they replaced some hardware in a box on the street.
So the CM1100 seems to be working now?
I have the exact same problem & scenario! Purchased from Costco a month ago and every 2-3 days internet connection dropped at some random time. On average, I had to reset my modem and router 5-7 times a day. Comcast tech came out, tested the line, recrimp connectors, and the internet was back online for a few day then the nightmare return.
Things I did differently
I decide to trace the line myself (from the demarcation point) and found a broken 2-Way Splitter in the attic, removed the bad unit, and add a coax coupler for a straight run. Finally figure out how to configure my router (new to 802.11ac router). I have Internet through modem but not through router for several days, so I cloned the MAC address of my computer to the router (CM1100 is picky with this). I didn't need to do this with previous routers.
I need help interpret the Event Log and Cable Connection chart. Thanks in advance.
Starting Frequency <tabindex=-1>Startup Procedure</tabindex=-1>
Procedure Status Comment Acquire Downstream Channel 663000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Security Enable BPI+ IP Provisioning Mode Honor MDD IPv6 only <tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords 1 Locked QAM256 33 663000000 Hz -2.7 dBmV 36.2 dB 938429531 1488 114 2 Locked QAM256 5 483000000 Hz 0.8 dBmV 38.0 dB 937270327 0 0 3 Locked QAM256 6 489000000 Hz -0.3 dBmV 37.8 dB 937273504 0 0 4 Locked QAM256 7 495000000 Hz 0.0 dBmV 37.6 dB 937277251 0 0 5 Locked QAM256 8 507000000 Hz 0.3 dBmV 37.4 dB 937280540 0 0 6 Locked QAM256 9 513000000 Hz 0.1 dBmV 37.5 dB 937284349 0 0 7 Locked QAM256 10 519000000 Hz 0.1 dBmV 37.5 dB 937288403 0 0 8 Locked QAM256 11 525000000 Hz -0.3 dBmV 37.3 dB 937291998 0 0 9 Locked QAM256 12 531000000 Hz -0.8 dBmV 36.9 dB 937299588 0 0 10 Locked QAM256 13 543000000 Hz 0.0 dBmV 37.2 dB 937303415 0 0 11 Locked QAM256 14 549000000 Hz -1.3 dBmV 36.7 dB 937307550 1 0 12 Locked QAM256 15 555000000 Hz -1.7 dBmV 36.8 dB 937311287 0 0 13 Locked QAM256 16 561000000 Hz -0.7 dBmV 37.1 dB 937315100 0 0 14 Locked QAM256 17 567000000 Hz -1.4 dBmV 37.0 dB 937318297 0 0 15 Locked QAM256 18 573000000 Hz -1.4 dBmV 37.0 dB 937322549 0 0 16 Locked QAM256 19 579000000 Hz -1.3 dBmV 36.9 dB 937325568 0 0 17 Locked QAM256 20 585000000 Hz -1.4 dBmV 36.9 dB 937334729 0 0 18 Locked QAM256 21 591000000 Hz -2.5 dBmV 36.6 dB 937339693 0 0 19 Locked QAM256 22 597000000 Hz -1.5 dBmV 36.7 dB 937342304 1 0 20 Locked QAM256 23 603000000 Hz -1.3 dBmV 36.8 dB 937346425 0 0 21 Locked QAM256 24 609000000 Hz -1.5 dBmV 36.7 dB 937349861 2 0 22 Locked QAM256 25 615000000 Hz -2.5 dBmV 36.3 dB 937354011 1 0 23 Locked QAM256 26 621000000 Hz -1.9 dBmV 36.6 dB 937357491 0 0 24 Locked QAM256 27 627000000 Hz -2.3 dBmV 36.2 dB 937361164 0 0 25 Locked QAM256 28 633000000 Hz -2.7 dBmV 36.3 dB 937365420 1 0 26 Locked QAM256 29 639000000 Hz -2.3 dBmV 36.3 dB 937368977 0 0 27 Locked QAM256 30 645000000 Hz -2.4 dBmV 36.2 dB 937372757 0 0 28 Locked QAM256 31 651000000 Hz -4.0 dBmV 35.4 dB 937376345 2 0 29 Locked QAM256 32 657000000 Hz -4.1 dBmV 35.6 dB 937380346 1 0 30 Locked QAM256 34 669000000 Hz -3.8 dBmV 35.8 dB 937384259 0 0 31 Locked QAM256 35 675000000 Hz -3.4 dBmV 35.3 dB 937386654 0 0 32 Locked QAM256 36 681000000 Hz -3.1 dBmV 36.1 dB 937385327 0 0 <tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power 1 Locked ATDMA 1 30100000 Hz 47.3 dBmV 2 Locked ATDMA 2 36500000 Hz 46.8 dBmV 3 Locked ATDMA 3 17300000 Hz 47.3 dBmV 4 Locked ATDMA 4 23700000 Hz 47.3 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 <tabindex=-1>Downstream OFDM Channels</tabindex=-1>
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 -0.2 dBmV 34.8 dB 1126 ~ 2969 799110390 447 0 2 Not Locked 0 0 0 Hz 3.8 dBmV 0.0 dB 0 ~ 4095 0 0 0 <tabindex=-1>Upstream OFDMA Channels</tabindex=-1>
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 Current System Time: Mon Jun 29 23:30:20 2020System Up Time: 5:45:45
So after finding the broken twoway splitter, did you remove this splitter and connect the modem directly? Splitters are not recomnended to use.
Test the CM modem with out the wifi router online to see if it maintains connection with just a wired PC connected.
Yes, I removed the broken 2-way splitter and replace with a coax coupler. Guess who installed the poor quality splitter? Comcast tech.
Yes, I tested modem with wired PC directly connected. So far, so good. I'll check back in two weeks and update the status.
