Re: [CM1200] Constant Internet Drop on Spectrum

Pibe38 · ‎2020-05-03

Hello,

A few days ago I decided to purchase my own modem. I originally purchased the Arris SB8200. 24 hours after activation I started having my connection drop every so often; it would come back up after a few minutes or sometimes I'd have to power cycle the modem.

Spectrum sent a tech because, even though the issues started right after I swapped from their modem to my own, they detected issues with the signal/line. The tech removed an unnecesary splitter and checked the lines. At the end of the visit, he said the levels looked ok. The next night I activated the CM1200 because I thought it could be a hardware issue since I had never had line issues, and the timing seemed too coincidental. Also, Spectrum removed the SB8200 from their list of approved modems literally the day after I activated it, so I decided to exchange it for the CM1200 which is still on the list.

However, my connection drop issues have gotten worse. I can't go an hour witouth the connection dropping. The modem doesn't actually reboot itself as I have been able to see under System Up Time, but it definately loses connection and picks it back up after a few minutes. There is another tech scheduled to come in tomorrow, but I would like to arm myself with information to get this solved as soon as possible.

Log and Cable Connection details to follow...

Thank you in advance for any possible assistance.

Pibe38 · ‎2020-05-03

Adding as attachment, let me know if there's a better format.

Thank you.

FURRYe38 · ‎2020-05-03

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.

Pibe38 · ‎2020-05-03

Thank you @FURRYe38, are those standard things to check or do you see something on the logs that could indicate an issue?

FURRYe38 · ‎2020-05-03

Those are standard things to check first always.

Seems that if you had a SB8200 that exhibited problems and now have a CM1200 thats having problems, seems like this maybe a service or line issue.

Mexicant11 · ‎2020-06-27

Please update when you have an answer. I too am having the same problems after choosing to upgrade my modem. I've had three service calls with three different text coming out. The last tech today, replaced all the lines, I mean every line coming down from the pole into my house. Sobline integrity is not the issue. He could not figure out what was wrong. On 3 out of 4 upstream channels had no signal.the only solution was to provide their own 3.1 modem. I would rather use my CM1200. So any additional info would be helpful.

FURRYe38 · ‎2020-06-27

If the ISP modem works and the CM doesn't after all that, I would return the CM modem or get it replaced with another and try again.

@Mexicant11 wrote:
Please update when you have an answer. I too am having the same problems after choosing to upgrade my modem. I've had three service calls with three different text coming out. The last tech today, replaced all the lines, I mean every line coming down from the pole into my house. Sobline integrity is not the issue. He could not figure out what was wrong. On 3 out of 4 upstream channels had no signal.the only solution was to provide their own 3.1 modem. I would rather use my CM1200. So any additional info would be helpful.

LindaMc · ‎2020-08-11

I am having the same issue for weeks now. Have just requested the 2nd tech call with ISP. Beyond maddening. The issue started after the news about the Netgear security vulnerability. I’m planning to return this modem and switch brands.

FURRYe38 · ‎2020-08-11

What security vulnerability would that be?

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.
Be sure to power OFF the modem for 1 minute them back ON.

@LindaMc wrote:
I am having the same issue for weeks now. Have just requested the 2nd tech call with ISP. Beyond maddening. The issue started after the news about the Netgear security vulnerability. I’m planning to return this modem and switch brands.

vkdelta · ‎2020-08-11

US is partial service.

You only have 1 US locked and there are T3 timeouts on 3 US.

Did you have logs with SB8200? Does it show the same issue?

do you have screenshots with charter leased modem? (I dont think they provide GUI access and you may not be able to see even if there is a problem or not)

FURRYe38 · ‎2020-08-12

https://community.netgear.com/t5/Cable-Modems-Routers/Cm1200-modem-incessantly-dropping-connection/m...

choll · ‎2020-12-06

I'm also having this problem. I bought the cable model in October and it's been fine until now. Today it dropped the Internet 3 or 4 times. Nothing has changed (unless it updated itself with new code). It's hardware 1.01 and firmware V2.02.03. The log includes:

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=08:36:c9:42:65:18;CMTS-MAC=00:a5:bf:0f:ea:ad;CM-QOS=1.1;CM-VER=3.1;

Dynamic Range Window violation

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:42:65:18;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Honoring MDD; IP provisioning mode = IPv4

There's more in the attached logfile. Any ideas why it should start having problems now?

Thanks,

Chris

FURRYe38 · ‎2020-12-07

Have the ISP check the signal and line quality UP to the modem.

Be sure the ISP provisions the modem correctly.
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.
Be sure to power OFF the modem for 1 minute them back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...

@choll wrote:
I'm also having this problem. I bought the cable model in October and it's been fine until now. Today it dropped the Internet 3 or 4 times. Nothing has changed (unless it updated itself with new code). It's hardware 1.01 and firmware V2.02.03. The log includes:

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=08:36:c9:42:65:18;CMTS-MAC=00:a5:bf:0f:ea:ad;CM-QOS=1.1;CM-VER=3.1;
Dynamic Range Window violation
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:42:65:18;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Honoring MDD; IP provisioning mode = IPv4

There's more in the attached logfile. Any ideas why it should start having problems now?
Thanks,
Chris

Lito628 · ‎2021-02-08

Having the same issues as others. We need a solution here. I’ve tried ALL the standard procedure and had my ISP check everything. Cables are good, router is good, did reboot, update and factory reset. Nothing is working to fix the issue. Why is this not being solved by now? I need help??

FURRYe38 · ‎2021-02-08

https://community.netgear.com/t5/Cable-Modems-Routers/CM1200-Drops-Internet/td-p/2054250/jump-to/fir...

@Lito628 wrote:
Having the same issues as others. We need a solution here. I’ve tried ALL the standard procedure and had my ISP check everything. Cables are good, router is good, did reboot, update and factory reset. Nothing is working to fix the issue. Why is this not being solved by now? I need help??

MisFiTkEv · ‎2021-02-17

to everyone having this issue...you are not alone. Same here. 3 visits by techs from spectrum---replaced cable from pole to home 1x. Still having issues. Frequent disconnects. basically, my cm1200 is a pos now. I suspect HIGHLY due to lack of firmware update pushes by Spectrum. Apparently, our CM1200 on spectrum has the oldest firmware available to any provider.

But hey, who am i?

Its a recommended cable modem---with terrible service and no fix.

FURRYe38 · ‎2021-02-17

If you can't get spectrum to update FW on the CM modem, you best recommendation would be to get one of there modems, ask for a modem only unit and use there HW. Seems that Spectrum doesn't like messing with user owned modems. Shame too. More resent FW on my 1200 with my ISP works great. Same Spectrum won't push FW. It's up to them.