Intermittent connection, modem refresh

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Yep. In the second example, the SNR's are indeed too low / out of spec. It appears that there is intermittent noise ingress into the line(s) somewhere. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connection quality, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.

Good luck !

SNR improved.  Upstream power still below 30

1 Locked QAM256 30 633.0 -2.0 38.2 55 0    2 Locked QAM256 1 465.0 2.8 40.1 17 0    3 Locked QAM256 2 471.0 2.6 40.1 23 0    4 Locked QAM256 3 477.0 2.4 39.9 26 0    5 Locked QAM256 4 483.0 2.3 40.0 25 0    6 Locked QAM256 5 489.0 2.0 39.9 30 0    7 Locked QAM256 6 495.0 1.7 39.7 37 0    8 Locked QAM256 7 501.0 1.3 39.5 28 0    9 Locked QAM256 8 507.0 1.1 39.3 49 0    10 Locked QAM256 9 513.0 0.5 39.1 62 0    11 Locked QAM256 10 519.0 0.4 39.1 55 0    12 Locked QAM256 11 525.0 0.4 39.1 48 0    13 Locked QAM256 13 537.0 0.5 39.2 47 0    14 Locked QAM256 14 543.0 0.3 39.1 46 0    15 Locked QAM256 15 549.0 0.2 38.9 51 0    16 Locked QAM256 16 555.0 0.2 39.2 58 0    17 Locked QAM256 17 561.0 -0.1 38.8 61 0    18 Locked QAM256 18 567.0 -0.3 38.7 68 0    19 Locked QAM256 19 573.0 -0.4 38.8 61 0    20 Locked QAM256 20 579.0 -0.6 38.9 70 0    21 Locked QAM256 21 585.0 -0.6 38.9 45 0    22 Locked QAM256 22 591.0 -0.8 38.7 51 0    23 Locked QAM256 23 597.0 -1.0 38.6 61 0    24 Locked QAM256 24 603.0 -1.1 38.6 55 0    25 Locked QAM256 25 609.0 -1.3 38.5 59 0    26 Locked QAM256 26 615.0 -1.5 38.4 70 0    27 Locked QAM256 27 621.0 -1.7 38.3 52 0    28 Locked QAM256 28 627.0 -1.8 38.3 60 0    29 Locked OFDM PLC 29 672.0 -2.7 37.0 50625691 0    30 Locked QAM256 31 639.0 -2.2 38.1 62 0    31 Locked QAM256 32 645.0 -2.3 38.2 50 0    32 Locked QAM256 33 651.0 -2.5 37.9 63 0

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)    1 Locked SC-QAM 53 5120 17.3 28.8    2 Locked SC-QAM 54 5120 23.7 29.0    3 Locked SC-QAM 55 5120 30.1 29.8    4 Locked SC-QAM 56 5120 36.5 29.8

Well, new - new motorola mb8611 seems to be doing better, or some changes were made on Comcast's end.  The biggest difference I see is the increase in downstream power.  I still see some t-3 time outs, and synch failures.....but the modem has not reset yet, going on 14 hours.

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected    1 Locked QAM256 30 633.0 -0.5 29.2 191718 0    2 Locked QAM256 1 465.0 4.7 31.4 1504 0    3 Locked QAM256 2 471.0 4.5 31.3 1787 0    4 Locked QAM256 3 477.0 4.3 31.0 2837 0    5 Locked QAM256 4 483.0 4.1 31.0 3171 0    6 Locked QAM256 5 489.0 3.8 30.8 5123 0    7 Locked QAM256 6 495.0 3.5 30.5 7172 0    8 Locked QAM256 7 501.0 3.1 30.3 13561 0    9 Locked QAM256 8 507.0 2.9 30.1 18731 0    10 Locked QAM256 9 513.0 2.4 29.8 60458 0    11 Locked QAM256 11 525.0 2.1 29.7 68747 0    12 Locked QAM256 12 531.0 2.2 29.5 89240 0    13 Locked QAM256 13 537.0 2.2 29.9 36049 0    14 Locked QAM256 14 543.0 2.1 29.9 41940 0    15 Locked QAM256 15 549.0 1.9 29.8 51487 0    16 Locked QAM256 16 555.0 1.9 29.9 48316 0    17 Locked QAM256 17 561.0 1.7 29.7 75831 0    18 Locked QAM256 18 567.0 1.5 29.5 96267 0    19 Locked QAM256 19 573.0 1.3 29.5 95853 0    20 Locked QAM256 20 579.0 1.2 29.6 88373 0    21 Locked QAM256 21 585.0 1.1 29.6 72288 0    22 Locked QAM256 22 591.0 0.9 29.5 90252 0    23 Locked QAM256 23 597.0 0.7 29.5 99274 0    24 Locked QAM256 24 603.0 0.5 29.4 109144 0    25 Locked QAM256 25 609.0 0.3 29.4 116283 0    26 Locked QAM256 26 615.0 0.1 29.3 152987 0    27 Locked QAM256 27 621.0 -0.1 29.3 145622 0    28 Locked QAM256 28 627.0 -0.2 29.3 152995 0    29 Locked OFDM PLC 29 672.0 -1.2 28.5 77308333 425169244    30 Locked QAM256 31 639.0 -0.7 29.1 278006 0    31 Locked QAM256 32 645.0 -0.7 29.2 210251 0    32 Locked QAM256 33 651.0 -1.0 29.2 265454 0

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)    1 Locked SC-QAM 53 5120 17.3 28.8    2 Locked SC-QAM 54 5120 23.7 28.5    3 Locked SC-QAM 55 5120 30.1 29.0    4 Locked SC-QAM 56 5120 36.5 29.0

So to recap.  I had a month old mb8611 and was having issues.  Tech visited and replaced connections from tap to modem.  Still had modem refreshes.  Contacted Amazon, they sent out replacement mb8611.  In the meantime, we connected the Comcast gateway that I had not returned yet.......still had drops.  I connected the brand new mb8611 yesterday and the connection numbers posted today are from that.  Here is the event log.  Comcast is sending a tech again today.

Glad I didn't cancel the tech visit for today.  Bad tap.  Service ticket is in and they will come out in the next few weeks to work on the tap.  Hopefully that does it.

Good luck ! Please post back With how things turn out.

I hadn't heard anything from Comcast about the ticket to replace the tap, so I reached out the other day.  They suggested a third tech visit to hopefully get things moving along.  Well, third times the charm.  An actual Xfinity technician, not a contractor, came out this morning and tested everything out again.  I have a long driveway....over 1000feet, so a line comes in underground from the road and goes to a pedestal about 100feet from the house.  The line from the pole to the tap was fine, tap was bad at the pedestal, and the line underground from the tap to the house was bad.  The service technician called in to maintenance to have the tap repaired.  So, a maintenance tech came and made that repair and also swapped out an amp on one of the poles down the road.  The service tech ran a new line (will need to get buried at some point) from the tap to the house, replace the connection box on the outside of the house, and ran a new line from that box all the way to the modem.  A supervisor also came out and checked everything over.  Looking at the numbers now, the downstream power is above 0, and the upstream power is now above 40.  It seems that all is well and my service should no longer be interrupted.

On a side note, Xfinity needs to address the call center (1-855-433-2886) technicians calling to try and cancel appointments.  Ahead of the second tech visit, and again ahead of the third visit, someone called from Xfinity to suggest that the problem had been fixed and I shouldn't need an appointment.  These same people suggested previously that my modem was the problem, which prompted me to exchange a month old modem.  I knew that xfinity had not been out to fix the tap and that my numbers were out of spec, so why would they call and suggest otherwise?

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected    1 Locked QAM256 25 609.0 1.4 40.4 1 0    2 Locked QAM256 1 465.0 4.4 41.3 0 0    3 Locked QAM256 2 471.0 4.3 41.4 0 0    4 Locked QAM256 3 477.0 4.1 41.3 0 0    5 Locked QAM256 4 483.0 4.0 41.5 0 0    6 Locked QAM256 5 489.0 3.7 41.3 0 0    7 Locked QAM256 6 495.0 3.5 41.2 0 0    8 Locked QAM256 7 501.0 3.1 41.0 2 0    9 Locked QAM256 9 513.0 2.4 40.7 0 0    10 Locked QAM256 10 519.0 2.3 40.9 1 0    11 Locked QAM256 11 525.0 2.4 40.8 1 0    12 Locked QAM256 12 531.0 2.5 40.9 0 0    13 Locked QAM256 13 537.0 2.5 40.9 1 0    14 Locked QAM256 14 543.0 2.5 40.9 1 0    15 Locked QAM256 15 549.0 2.3 40.8 2 0    16 Locked QAM256 16 555.0 2.4 40.9 0 0    17 Locked QAM256 17 561.0 2.2 40.8 0 0    18 Locked QAM256 18 567.0 2.1 40.7 0 0    19 Locked QAM256 19 573.0 2.0 40.6 1 0    20 Locked QAM256 20 579.0 1.9 40.7 3 0    21 Locked QAM256 21 585.0 1.9 40.8 2 0    22 Locked QAM256 22 591.0 1.7 40.6 0 0    23 Locked QAM256 23 597.0 1.6 40.7 1 0    24 Locked QAM256 24 603.0 1.5 40.5 0 0    25 Locked QAM256 26 615.0 1.2 40.4 0 0    26 Locked QAM256 27 621.0 1.1 40.4 0 0    27 Locked QAM256 28 627.0 1.1 40.4 0 0    28 Locked OFDM PLC 29 672.0 0.4 39.6 459043 0    29 Locked QAM256 30 633.0 0.9 40.3 0 0    30 Locked QAM256 31 639.0 0.7 40.2 1 0    31 Locked QAM256 32 645.0 0.7 40.2 1 0    32 Locked QAM256 33 651.0 0.6 40.2 0 0

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)    1 Locked SC-QAM 53 5120 17.3 42.0    2 Locked SC-QAM 54 5120 23.7 42.3    3 Locked SC-QAM 55 5120 30.1 42.3    4 Locked SC-QAM 56 5120 36.5 42.5