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Disconnecting Constantly Ever Since Snow Storm

Pwrtackl75Pwrtackl75 Posts: 6 ✭✭
edited June 17 in Internet 2020 Archive Dec 16, 2020

I've been using a personal modem (Netgear CM1200) for about a year on 400/25Mbps (483/22 actual) service for about a year now with no issues. I didn't lose internet during this recent snow storm until about 2 days afterwards. It's been a week since the storm and I'm still having issues after a tech visit.

A tech came out about 4 days after the storm and said that the signal became too hot. He added more pads. 12dB total I believe on the downstream and a few dB on the upstream. I didn't see the upstream pad he put in. He thinks Spectrum turned up the power after the storm to compensate for other people's issues. I'm near the end of the line and my signal is too hot apparently. Doesn't sound like a bad problem to have normally.

We looked at my modem power levels together and he said it was ideal like this (-0.8 to -3.9dBmV downstream.) Obviously it's coming in about 12dB higher until his 12dB pad so he could have had it higher if he wanted. The previous tech, who came out to remove an old Time Warner cable tv filter from the pole, said the same thing about these levels. Both techs had agreed I was good to go to run 980Mbps service.

Here's some info on my system. Desktop gaming pc with 10ft CAT8 to Linksys EA9500 router with 1ft CAT8 to Netgear CM1200 modem (personal) with ~30ft RG6 to ~180ft RG11 to Spectrum outdoor box on the pole. Tech replaced all coax connectors for good measure although he tested the line from the modem out the spectrum box and said everything was "Great."

Below is the data from my modem including all levels and error log. Please take a look and see if there's any obvious problems. Any help is appreciated. When the internet goes down I log into the modem and see that the upstream channels 1 & 2 are unlocked. I can send more information as well if needed.

Accepted Answers

  • rocketjetzrocketjetz Posts: 162 ✭✭✭✭
    edited December 2020 Dec 16, 2020 Accepted Answer

    your Power and SNR look to be within spec on Downstream. Your Upstream Power looks way high to me.

    Upstream Power:

    The lower this number is, the better. If it is above 55, you may want to see if you can reconfigure your splitters. Anything above 57 is not good and should be fixed ASAP. (This is getting pretty close to not being able to connect.)

    Normally I've seen these numbers around 42-48

    Upstream Power / Modulation(37dbmV to 55dbmV) - the strength of signal transmitted by the cable modem

    Generally a lower this number is better. Above 53dB will most likely cause problems, over 57dB and you probably won't be able to connect. Ideally between 42 and 50dB. Lower than 40 may start introducing some packet loss (especially if you have much noise on the line). If you hit 58 the modem will likely drop the connection and resync.

    Doesn't appear the attenuator is working correctly on the upstream. "a few dB on the upstream"

    obviously the upstream needs more than few dB......

  • misterjmisterj Posts: 194 ✭✭✭✭
    Dec 16, 2020 Accepted Answer

    Pwrtackl75, I suggest no more US attenuation. Let the Spectrum people correct their network. Here is what I think is happening. When the modem establishes a connection, it sends data to the ISP and checks the response. If necessary, the modem will increase the US power. That is what the 59 dBmv is about - the poor modem is boosting power trying to be heard at the ISP. More attenuation will not lower this number because it is measured inside the modem. Something is wrong in the Spectrum network which is damaging your US signal. Enjoy, John.

  • misterjmisterj Posts: 194 ✭✭✭✭
    Dec 16, 2020 Accepted Answer

    Pwrtackl75, I talked to my modem support (Arris SB8200). Only a few modems allow the user to boost the US levels but I think most modern modems will raise their US power. I suspect ISPs do not like users being able raise their levels and it may be blocked in the firmware.

    "...after the tech left. It was good for 2 days..," Sounds like they fixed their network but you are stuck with 12 dB cut attenuator . If you know where the attenuator is, I would suggest you remove it, reboot your modem and see how it works. If you do not know then you will have to call them. Please report back. Thanks, John.

  • Lake802Lake802 Posts: 97 ✭✭✭✭
    Dec 19, 2020 Accepted Answer

    Greetings Pwrtrack - sorry to hear you are having service issues. Misterj gave great advice in regard to get rid of 12db attenuators . The Recurring T3 errors are the problem. Would temporarily allow them to replace with Spectrum supplied modem to help you get signals stable , reliable and in spec.

    The anecdotal evidence regarding the netgear cm1200 borders on non-sense and are not the substantive issue.

    Main focus is to get your signals stable, reliable consistent and in spec. Once that is accomplished the modem/router combo you choose is entirely up to you.

    Most folks will end up with a Spectrum supplied modem and add the preferred router/wifi box/solution of their choice.

    Please let us know how it goes after next tech appointment even if it is scheduled 5 days out.


  • misterjmisterj Posts: 194 ✭✭✭✭
    Dec 16, 2020

    Pwrtackl75, please see here -

    You should consider getting a Spectrum modem (at least to test) to see it that corrects the problem. Enjoy, John.

  • Pwrtackl75Pwrtackl75 Posts: 6 ✭✭
    Dec 16, 2020

    I think you're right @rocketjetz . I hadn't looked up the transmit power range. It had been in the 30's-40's all along and even after the tech left. It was good for 2 days and now upstream is hot. It seems that they're still playing with their system? It'll be a few more days to get a tech back out again. I should probably buy some attenuators myself. Haha

  • Pwrtackl75Pwrtackl75 Posts: 6 ✭✭
    edited December 2020 Dec 16, 2020

    @misterj another good point. I never knew the modem accommodated different outputs on demand. I have an extended power output checkbox (which is unchecked) so it made me think it only had 2 levels. I'll push tech support to look closer at their own system if possible.

    The 483/23Mbps speeds have been consistent for a year with no outages and then this one storm event was the trigger for these issues. They obviously haven't corrected their system back to normal yet.

  • Pwrtackl75Pwrtackl75 Posts: 6 ✭✭
    Dec 17, 2020

    Status Update: Spectrum addressed some outages they said were in my neighborhood yesterday and now my internet isn't dropping. The Upstream power is still pinned at 59dBmV though and the modem log is showing the following messages about every 6 minutes it seems. I'm not sure if it's a normal event. I called Spectrum and they said they'll have a tech out in 5 days to take a look at it. They agreed that they're still seeing errors on their end. I'll attach a fresh screenshot of my levels for reference.

  • misterjmisterj Posts: 194 ✭✭✭✭
    Dec 17, 2020

    Pwrtackl75, please make sure that you have restarted your modem since their report. Do you know where the 12 dB attenuator is? If it is in your demarc, please remove it, reboot the modem and see if the level is better. Thanks, John.

  • Jaded73Jaded73 Posts: 1
    Dec 21, 2020

    I don't know about this tech stuff. However I do know that I am sick and tired of my internet dropping out all of the time. I noticed the problem about 6-8 months after having service set up. I use the modem spectrum provided with their service. Ubee DVW32CB ....Whatever that means.

  • James_MJames_M Posts: 2,996 ADMIN
    edited December 2020 Dec 22, 2020

    I don't know about this tech stuff. However I do know that I am sick and tired of my internet dropping out all of the time. I noticed the problem about 6-8 months after having service set up. I use the modem spectrum provided with their service. Ubee DVW32CB ....Whatever that means.


    Sorry for any service issues. If you are seeking assistance for an internet related issue, we encourage you to start a new, separate post.


  • Pwrtackl75Pwrtackl75 Posts: 6 ✭✭
    Dec 22, 2020

    UPDATE: A new tech came today. I asked him to hook the line back up with no pads just so we could see the levels from the modem. DS was +9 to +12dBmV and US was running at 34.8dBmV (which I hear is close to noise floor and you want it a little higher). This tech wasn't a fan of the 12dB (bidirectional) and additional US pad that the previous tech put in. No wonder my modem was at 59dBmV US... He installed a splitter only and my levels are as shown below now.

    Internet is stable and the levels seem closer to ideal compared to before. The event log is populating with various new things. Event code 16 and 24 seem to be DOCSIS 3.1 related so I'm guessing it's fine since I'm running DOCSIS 3.0 on the 400Mbps plan. Not sure if there's anything I can do about it or if they won't be happy until I switch to DOCSIS 3.1 service (940/35).

    Downstream OFDM Channels didn't have Uncorrectable Codewords previously...

    Let me know what you think.

  • misterjmisterj Posts: 194 ✭✭✭✭
    Dec 23, 2020

    Pwrtackl75, looks good to me. How does the speed test? You look like you have a 3.0 and a 3.1 DS but no 3.1 US. Mine looks the same. My front panel shows 3.1 DS (Blue) and 3.0 US (Green). I would say, if it stays stable and test good speed, go with it. Thanks, John.

  • Pwrtackl75Pwrtackl75 Posts: 6 ✭✭
    Dec 23, 2020

    @misterj Holding at 483/23 on all speed tests. As good as it ever did. I'll test it now and then but it feels like it'll be good for another year barring more weird infrastructure changes.

  • misterjmisterj Posts: 194 ✭✭✭✭
    Dec 23, 2020

    Thanks, Pwrtackl75. I get 235 Mbps on my 200 Mbps service, so that is about exactly the same and as it should be! Hope you can ride this horse for a while! Enjoy, John.

  • rocketjetzrocketjetz Posts: 162 ✭✭✭✭
    Dec 24, 2020

    good for you Pwrtackl75......sometimes ALL it takes is persistence, patience, and several Spectrum techs ....hahahah😂🤣🙄

This discussion has been closed.