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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.
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.
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<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.
