Dynamic Range Window Violation

Oh no! I know how upsetting it can be when things don't work as expected. Let's take a look at the account and see what's going on with the service. 

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Please redact all of the CM MAC and the CMTS MAC addresses from your error log entries for your privacy. They are considered to be personal information. The posting of personally identifiable information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically. It flagged your post as "Private".

Quite welcome ! 

What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1 or here http://10.0.0.1 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

What is the exact make and model number of the modem / gateway device ?

Also. Please post those modem error log entries again. Copy and paste them into your next post but you'll need to redact all of the CM MAC and CMTS MAC addresses.

The modem is a Motorola MB8611.

Connection

Startup Sequence        Startup Step Status Comment       Acquire Downstream Channel 693000000 Hz Locked       Upstream Connection OK Operational       Boot State OK Operational       Configuration File OK       Security Enabled BPI+       Connection Status        System Up Time 5 days 21h:31m:24s         Network Access Allowed         Downstream Bonded Channels         Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected    1 Locked QAM256 41 693.0 1.0 40.1 3530 1183    2 Locked QAM256 13 525.0 2.7 41.2 9348 29150    3 Locked QAM256 14 531.0 2.9 41.2 7638 28100    4 Locked QAM256 15 537.0 2.8 41.2 9061 31327    5 Locked QAM256 16 543.0 2.9 41.1 5118 14289    6 Locked QAM256 17 549.0 3.0 41.2 7948 4151    7 Locked QAM256 18 555.0 2.1 40.8 5200 10999    8 Locked QAM256 19 561.0 2.1 40.9 5269 10776    9 Locked QAM256 20 567.0 2.4 41.0 5233 12498    10 Locked QAM256 21 573.0 2.3 40.9 7963 19006    11 Locked QAM256 22 579.0 2.0 40.6 5927 11871    12 Locked QAM256 23 585.0 2.4 40.9 9390 31491    13 Locked QAM256 24 591.0 3.4 41.1 10361 36080    14 Locked QAM256 25 597.0 3.9 41.0 8367 32298    15 Locked QAM256 26 603.0 3.1 40.7 9743 29556    16 Locked QAM256 27 609.0 2.9 40.7 5132 16515    17 Locked QAM256 28 615.0 3.1 40.8 5612 4408    18 Locked QAM256 29 621.0 2.6 40.7 10122 6980    19 Locked QAM256 30 627.0 2.2 40.5 9708 7718    20 Locked QAM256 31 633.0 2.0 40.3 9651 9821    21 Locked QAM256 32 639.0 0.9 40.1 6089 12786    22 Locked QAM256 33 645.0 0.0 39.7 4806 10218    23 Locked QAM256 34 651.0 0.7 39.9 7941 25729    24 Locked QAM256 35 657.0 1.9 40.4 10088 35417    25 Locked QAM256 36 663.0 2.7 40.6 6886 23122    26 Locked QAM256 37 669.0 2.4 40.5 7205 27283    27 Locked QAM256 38 675.0 2.2 39.9 5155 19471    28 Locked QAM256 39 681.0 1.8 40.4 4234 4416    29 Locked QAM256 40 687.0 1.4 40.3 4521 2685    30 Locked QAM256 42 699.0 1.6 40.2 3718 2078    31 Locked QAM256 43 705.0 1.5 40.3 4583 9107    32 Locked QAM256 44 711.0 1.1 40.1 4525 11130    33 Locked OFDM PLC 159 768.0 2.1 40.6 2744023 56707    Upstream Bonded Channels         Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)    1 Locked SC-QAM 9 5120 35.6 46.0    2 Locked SC-QAM 10 5120 29.2 45.5    3 Locked SC-QAM 11 5120 22.8 44.0    4 Locked SC-QAM 12 5120 16.4 43.0    5 Locked SC-QAM 13 1280 39.6 46.0

Here are some recent log entires again:

Range violation error typically occurs if your upstream has a difference between weakest and strongest that tries to exceed 6 dBmV. Your screen shot only shows about 3 dBmV, but it's possible one of them may occasionally get noise or some issue that tries to exceed the difference. Your signal strength goes up with higher frequency. I used to have the reverse issue.

The signal status values at that snapshot in time were OK but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) /  an upstream channel / return path impairment somewhere.

There are other signal stat values that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees (The Digital Care Team) who are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll the CMTS for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !