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CM1200 Modem Upstream LED Flashing - Spectrum Internet

WaveWarper
Aspirant

CM1200 Modem Upstream LED Flashing - Spectrum Internet

I've had this modem for just over a year and it started dropping signal a couple days ago. The upstream LED was flashing green so I had a tech from Spectrum come out and check on everything. They promptly swapped my CM1200 out for one of their modems and everything worked. This is really frustrating considering I paid around $200 for the modem.

Any ideas what could be causing the issue and why the tech couldn't find a solution? Should I have "Enable Extended Upstream Transmit Power" checked in the modem options?

Hardware Version1.01
Firmware VersionV1.02.01
CM CertificateInstalled

 

I'm getting a bunch of errors and warnings in the log like this when connecting the modem:

 

Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out
Critical (3)16 consecutive T3 timeouts while trying to range on upstream channel 8
Warning (5)Dynamic Range Window violation
Warning (5)RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
Error (4)Missing BP Configuration Setting TLV Type
Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 1 of 14
plemans
Guru

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

The full logs as well as the cable connection page helps. 

Take a screen snip of them and post them here. 

Message 2 of 14
FURRYe38
Guru

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

Please post the Connection status page that gives the power levels seen on each channel.

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...

Message 3 of 14
WaveWarper
Aspirant

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

Thanks for the response.I'm assuming/hoping the tech made those checks when he was trying to get it working. 


Connection status page attached.

 

 

Message 4 of 14
FURRYe38
Guru

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

You would need to check to be sure. 

 

Your power levels seems a bit high...

Heres mine:

Startup Procedure
ProcedureStatusComment
Acquire Downstream Channel837000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
SecurityEnabledBPI+
IP Provisioning ModeHonor MDDhonorMdd(4)
 
Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUncorrectables
1LockedQAM25631837000000 Hz-2.5 dBmV37 dB00
2LockedQAM2561651000000 Hz-2.5 dBmV36.4 dB00
3LockedQAM2562657000000 Hz-2.6 dBmV36.4 dB00
4LockedQAM2563663000000 Hz-2.3 dBmV36.6 dB00
5LockedQAM2564669000000 Hz-2.3 dBmV36.6 dB00
6LockedQAM2565675000000 Hz-2.1 dBmV36.7 dB00
7LockedQAM2566681000000 Hz-2 dBmV36.9 dB00
8LockedQAM2567687000000 Hz-1.8 dBmV36.8 dB00
9LockedQAM2568693000000 Hz-1.7 dBmV36.9 dB00
10LockedQAM2569699000000 Hz-1.5 dBmV37 dB00
11LockedQAM25610705000000 Hz-1.5 dBmV36.8 dB00
12LockedQAM25611711000000 Hz-1.3 dBmV36.9 dB00
13LockedQAM25612717000000 Hz-0.8 dBmV37.1 dB00
14LockedQAM25613723000000 Hz-1 dBmV36.9 dB00
15LockedQAM25614729000000 Hz-0.7 dBmV36.9 dB00
16LockedQAM25616741000000 Hz-0.6 dBmV37.1 dB00
17LockedQAM25617753000000 Hz-0.7 dBmV37.2 dB00
18LockedQAM25618759000000 Hz-0.9 dBmV37.1 dB00
19LockedQAM25619765000000 Hz-1.3 dBmV37.1 dB00
20LockedQAM25620771000000 Hz-1.3 dBmV37.2 dB00
21LockedQAM25621777000000 Hz-1.5 dBmV37.3 dB00
22LockedQAM25622783000000 Hz-1.7 dBmV37.3 dB00
23LockedQAM25623789000000 Hz-1.7 dBmV37.4 dB00
24LockedQAM25624795000000 Hz-1.9 dBmV37.3 dB00
25LockedQAM25625801000000 Hz-2.1 dBmV37.1 dB00
26LockedQAM25626807000000 Hz-2 dBmV37.2 dB00
27LockedQAM25627813000000 Hz-2 dBmV37.2 dB00
28LockedQAM25628819000000 Hz-2.4 dBmV36.9 dB00
29LockedQAM25629825000000 Hz-2.3 dBmV37.2 dB00
30LockedQAM25630831000000 Hz-2.3 dBmV37.1 dB00
31LockedQAM25632843000000 Hz-2.5 dBmV37 dB00
32Not LockedUnknown00 Hz0.0 dBmV0.0 dB00
 
Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA15120 Ksym/sec36000000 Hz38.8 dBmV
2LockedATDMA25120 Ksym/sec29000000 Hz37.5 dBmV
3LockedATDMA55120 Ksym/sec22000000 Hz38 dBmV
4LockedATDMA62560 Ksym/sec16000000 Hz37 dBmV
5Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
6Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
7Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
8Not LockedUnknown00 Ksym/sec0 Hz0.0 dBmV
 
Downstream OFDM Channels
ChannelLock
Status
Modulation /
Profile ID
Channel
ID
FrequencyPowerSNR /
MER
Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1Locked0 ,1 ,233547000000 Hz-4.0 dBmV36.5 dB1108 ~ 2987107438938876128590
2Not Locked000 Hz0 dBmV0.0 dB0 ~ 4095000
Message 5 of 14
WaveWarper
Aspirant

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

Thanks for that. They said the power seems fine (I just asked again). Is there anything I can do on the modem side to rule out it is not faulty? I want to be able to bring some ammo back to Spectrum so they can't punt it back. As of now their provided modem is working, so I don't have a lot of leverage. 

Message 6 of 14
plemans
Guru

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

You're actually the first person with a locked upstream on the ofdma channels I've seen. 

You're power levels are technically within spec. You didn't post your whole logs but the one had a dynamic window violation and t3 errors. Dynamic window violations usually occur when the power gets to high/low for a period of time. it can cause instabilities. 

Your power levels are also a little backwards.  Usually when you're power level on the upstream is high, it means you're close to the node so you tend to have a lower upstream level because it doesn't take as much power to communicate with the node. 

Is there an amplifier in the line? 

Also, have you tried checking off the "enable extended upstream transmit power"

Message 7 of 14
WaveWarper
Aspirant

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

The "power" box is right outside the window from the modem, so the cable run is pretty short. I'm not sure if there is amp or not though. I will try giving the checkbox a try.

 

Thank you!

Message 8 of 14
ctem81
Star

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

You are the victim of OFDMA being enabled on the upload channels. Modem running 1.02.01 breaks when OFDMA is enabled. You can read my journey here. https://www.dslreports.com/forum/r32832397-Netgear-CM1200-is-now-crap-OFDMA-just-enabled-on-upstream
Message 9 of 14
FURRYe38
Guru

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

Any progress on this? 


@WaveWarper wrote:

The "power" box is right outside the window from the modem, so the cable run is pretty short. I'm not sure if there is amp or not though. I will try giving the checkbox a try.

 

Thank you!


 

Message 10 of 14
WaveWarper
Aspirant

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

They came out and swapped my modem with theirs (which is free) and my speeds have been the same. I've honestly not put any more effort into it. Kind of a shame because this means NETGEAR is losing a customer and I probably wouldn't recommend someone get their own modem at this point. 

Message 11 of 14
FURRYe38
Guru

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

You might try to contact NG support and your the ISP, have them push FW to the modem. Seems like the other user that posted reported v3 is working on there CM1200 thats on Spectrum. NG seems to have FW that would hopefully solve this for you. But its up to the ISP to push it. You might ask for escalated support from you ISP about this. I'm not on Spectrum, however my CM1200 works great. 

 

Good Luck. 


@WaveWarper wrote:

They came out and swapped my modem with theirs (which is free) and my speeds have been the same. I've honestly not put any more effort into it. Kind of a shame because this means NETGEAR is losing a customer and I probably wouldn't recommend someone get their own modem at this point. 


 

Message 12 of 14
Marksa17
Aspirant

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

I read through your post, and one year later seems like the same issue is happening. Is the only recourse to buy another modem?!!? This one is slightly over a year old only just started having issues. Still running the same firmware too.  Like OP I've had 3 tech visits, swapped out lines, added/removed/added again amplifier.  But constant issues. ISP said maybe an issues with  a Node, but to be honest I don't know what that means. I was given the number to the supervisor directly for updates, but I'll let you guess how many times I've spoken to him.   

 

I'll take any/all suggestions, tips, magic enchament spells.. what ever you got. 

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 13 of 14
Marksa17
Aspirant

Re: CM1200 Modem Upstream LED Flashing - Spectrum Internet

My specs if anyone cares to take a look. 

Model: CM1200|Nighthawk Multi-Gig Speed Cable Modem
Message 14 of 14
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