Intermittent Drops - T3 Time outs

[Erdosain]

Hoping others who may have similar issues are able to help me:

I've been paying for gigabit service.  I have my own cable modem (a netgear cm1200) and use google wifi as my router.  For the last couple of months, I have been getting intermitten internet drops that last anywhere from 1 -5 minutes.   It can happen as few as a couple of times in one day, and as many as a dozen times in a day.  It has made working from home extremely challenging as I remote into my employers system using Cisco Worspace, and the connection kicks me frequently.

I've been looking at the error logs in my router and I seem to be getting T3 and T4 timeouts.  I checked the wiring inside my house and it looks good.  It's a single cable from outside my house that goes into the router - no splitters at all.  The cable outside my house looks a little banged up.

Here's the issue - I've tried reaching out to Comcast support, and it's been a nightmare.  All that happens is that they reset my router.  A tech came out right before the whole Covid 19 pandemic started and he said that the signal seemed fine.  Suggested I swap out the router/replace it with the xfinity gateway.  Anyone having similar issues?

[EG]

What do the modem's signal stats look like ? 

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.

What is the exact make and model number of the modem ?

[Erdosain]

Netgear CM1200 -Nighthawk Multi-Gig Modem.

Here's the signal info:

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Frequency start Value

This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.

Starting Frequency

Startup Procedure

Procedure Status Comment Acquire Downstream Channel 525000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Security Enabled BPI+ IP Provisioning Mode Honor MDD honorMdd(4)

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 13 525000000 Hz 5.1 dBmV 40.8 dB 0 0 2 Locked QAM256 10 507000000 Hz 5.4 dBmV 41 dB 0 0 3 Locked QAM256 11 513000000 Hz 5.3 dBmV 40.9 dB 0 0 4 Locked QAM256 12 519000000 Hz 5 dBmV 40.9 dB 0 0 5 Locked QAM256 14 531000000 Hz 5 dBmV 40.8 dB 0 0 6 Locked QAM256 15 537000000 Hz 5.1 dBmV 40.8 dB 0 0 7 Locked QAM256 16 543000000 Hz 5.2 dBmV 40.7 dB 0 0 8 Locked QAM256 17 549000000 Hz 5.4 dBmV 40.6 dB 0 0 9 Locked QAM256 18 555000000 Hz 5.6 dBmV 40.8 dB 0 0 10 Locked QAM256 19 561000000 Hz 5.6 dBmV 40.7 dB 0 0 11 Locked QAM256 20 567000000 Hz 5.5 dBmV 40.6 dB 0 0 12 Locked QAM256 21 573000000 Hz 5.3 dBmV 40.5 dB 0 0 13 Locked QAM256 22 579000000 Hz 5.2 dBmV 40.6 dB 0 0 14 Locked QAM256 23 585000000 Hz 5.2 dBmV 40.5 dB 0 0 15 Locked QAM256 24 591000000 Hz 5.4 dBmV 40.5 dB 0 0 16 Locked QAM256 25 597000000 Hz 5.9 dBmV 40.6 dB 0 0 17 Locked QAM256 26 603000000 Hz 6 dBmV 40.6 dB 0 0 18 Locked QAM256 27 609000000 Hz 6.2 dBmV 40.6 dB 0 0 19 Locked QAM256 28 615000000 Hz 6.1 dBmV 40.5 dB 0 0 20 Locked QAM256 29 621000000 Hz 6.1 dBmV 40.5 dB 0 0 21 Locked QAM256 30 627000000 Hz 5.9 dBmV 40.5 dB 0 0 22 Locked QAM256 31 633000000 Hz 6 dBmV 40.6 dB 0 0 23 Locked QAM256 32 639000000 Hz 6.6 dBmV 40.7 dB 0 0 24 Locked QAM256 34 645000000 Hz 7 dBmV 40.8 dB 0 0 25 Locked QAM256 35 651000000 Hz 7.6 dBmV 40.9 dB 0 0 26 Locked QAM256 36 657000000 Hz 8.1 dBmV 41.1 dB 0 0 27 Locked QAM256 37 663000000 Hz 8.2 dBmV 41 dB 0 0 28 Locked QAM256 38 669000000 Hz 8.1 dBmV 41 dB 0 0 29 Locked QAM256 39 675000000 Hz 8 dBmV 40.5 dB 0 0 30 Locked QAM256 40 681000000 Hz 7.8 dBmV 40.8 dB 0 0 31 Locked QAM256 41 687000000 Hz 8.3 dBmV 41 dB 0 0 32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0

Upstream Bonded Channels

Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power 1 Locked ATDMA 1 5120 Ksym/sec 36500000 Hz 44 dBmV 2 Locked ATDMA 2 5120 Ksym/sec 30100000 Hz 43.3 dBmV 3 Locked ATDMA 3 5120 Ksym/sec 23700000 Hz 42.3 dBmV 4 Locked ATDMA 4 5120 Ksym/sec 17300000 Hz 41 dBmV 5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

Downstream OFDM Channels

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 ,1 ,2 ,3 33 693000000 Hz 9.1 dBmV 40.4 dB 1108 ~ 2987 66503597 8865565 0 2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0

Upstream OFDMA Channels

Channel Lock Status Modulation / Profile ID Channel ID Frequency Power 1 Not Locked 0 0 0 Hz 0 dBmV 2 Not Locked 0 0 0 Hz 0 dBmV

Extended Upstream Transmit Power

Enable Extended Upstream Transmit Power

Current System Time:Sun Jun 07 18:07:52 2020

System Up Time:01:43:09

[Erdosain]

So for what it's worth, I spent an hour with Comcast customer support yesterday.  They reset the cable modem for the 100th time.  They can see there's an issue and told me they would send a tech to see if there is an issue with the cable outside my house.  When we got to the point where they were going to schedule the tech, it turns out that they can't because of Covid-19 or so they claim.  Confusingly, they claimed that someone would reach out to me within 24 hours to schedule the visit seperately.  As I expected, I never heard back.

It must be nice to be a monopoly.

[rrmm07]

@Erdosain any luck with CM1200 & Comcast ? I am also facing the same issue.  Comcast scheduled a tech to look into it. He/She will come next week.  

[Erdosain]

@rrmm07:

Yes, it took two tech visits (one in February and one in July), but it looks like Comcast finally resolved the issue.  The wiring inside the house was fine, but there seems to have been an issue with the connection to the line at the cable box itself.   Since that was fixed I have had no more drops.  My supposedly gigabit connection, however, caps out at around 510Mpbs (hardwired to the cable modem for testing).   I've reached out to Comcast about the speeds, but at this point I'm just happy to have reliable internet - regardless of speed.

One thing I learned in this whole 5 month ordeal (hard to believe it was this long); do not believe the tech when they blame your cable modem or router.  I ended up swapping both out, and needlessly spending over $500 to do so (I admiteddly got a nicer cable modem and air mesh system than I previously had) when the problem was with the line, as I had told the first tech to begin with.  I complained to Comcast, who has made no effort to even provide a credit for almost half a year of terrible service. 

Good luck with it!