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Jdro86's avatar
Jdro86
Aspirant
Nov 30, 2020

CM1100 keeps dropping connection, using Spectrum

Hi All,

 

I bought a CM1100 about two weeks ago; it worked fine for exactly one week.  Last Tuesday I had network issues, the connectivity dropped and the modem had issues re-resolving to the CMTS.  Happened every day through Sunday.  Called Spectrum and they had a tech come out, said the signal was too strong.  He substituted a two-way splitter with a three-way and said the signal is now good.  Sure enough 2 hours later I get a drop again and am unable to re-gain internet with the CM1100.  I plug in my old TP-Link modem and I get back online immediately.  

 

This is from the old modem that i currently have hooked up:

Channel Status Modulation Channel ID Frequency Power SNR
1LockedQAM2562285000000 Hz4.6 dBmV36.2 dB
2LockedQAM2561279000000 Hz4.6 dBmV36.5 dB
3LockedQAM2563291000000 Hz4.5 dBmV36.2 dB
4LockedQAM2564297000000 Hz5.0 dBmV36.5 dB
5LockedQAM2569327000000 Hz5.6 dBmV36.9 dB
6LockedQAM2566309000000 Hz5.2 dBmV36.5 dB
7LockedQAM2567315000000 Hz5.0 dBmV36.4 dB
8LockedQAM2568321000000 Hz5.2 dBmV36.5 dB
Upstream Bonded Channels

Channel Status Channel Type Channel ID Symbol Rate Frequency Power
1LockedATDMA25120 ksym/sec24200000 Hz47.5 dBmV
2LockedATDMA45120 ksym/sec37000000 Hz48.3 dBmV
3LockedATDMA35120 ksym/sec30600000 Hz47.8 dBmV
4Not LockedUnknown00 ksym/sec0 Hz0.0 dBmV

 

These are slightly lower than what I was seeing on the CM1100 but only by about 2-3 dB.  

 

When I was getting network drops I was getting all sorts of errors in the log; T3 timeouts, Mismatch between Calculated value for P1.6hi, no ranging response received, followed by a bunch of DHCP errors.  None of these are happening with the old modem. 

 

Does anyone have any advice here?  Based on the errors and what I've read it seems like the signal strength might be too strong still, however the power values seem to be within useable range.   Would an Attenuator work here?  I know if I ask Spectrum to come back out they're just going to blame my equiptment and not the line. Additionally, when the CM1100 is up and running I am getting about 700mb down when I'm only paying for 400, perhaps this is an indication that the signal is way too strong?  

 

Or - does it seem like the modem is faulty and I should try replacing it before I do anything else?


Thanks in advance for any help!  

Justin

 

 

7 Replies

  • FURRYe38's avatar
    FURRYe38
    Guru - Experienced User
    Nov 30, 2020

    Is LAG enabled on the modem? 

     

    What happens if you remove ALL splitters? 

     

    Do you have Extended Upstream Transmit Power listed on the Cable Connections page? 

     

     

    • Jdro86's avatar
      Jdro86
      Aspirant
      Nov 30, 2020

      LAG is not enabled.

       

      The other line coming out of the splitter is to our cable box.  I can try at some point to see if any of the diagnostics change, but might be a bit of a burden to keep the box disconnected waiting for a network drop.  

       

      I don't believe Extended Upstream Transmit Power was listed but will check later.  

      • Jdro86's avatar
        Jdro86
        Aspirant
        Dec 04, 2020

        Ok, removed splitter, tried plugging directly into the line.  Had downstream power from 13-18.  Upstream channels were between 40-41.  I reinstalled the splitter immediately after and got downstream power from about 5-10; upstream was 47-48.  Left it plugged into the splitter last night and had a drop again at 5AM this morning, got a warning about high power signals, and had another drop half an hour ago that didn't resolve quickly so I had to switch back to my old modem.  Old DOSCSIS 3.0 TP-link modem is now getting downstream power from 4-6 and upstream are all at about 47.  I have been using this modem for 4 years and have had no issues (however, modem doesn't support bandwidth upgrade, hence new modem).  

         

        I had also bought a 6db attenuator, on my CM1100 it got my downstream down to right around 0, upstream was at 53-54.  I didn't have a network drop but my throughput sucked and I had a lot of uncorrectables.  

         

         

        Is there anything else I can do here myself? It seems to me like I am still having power issues.  Should I try adding in another splitter (any recommendations on which)?  I can have Spectrum come out but am skeptical that they will be able to do anything.