Repeated/intermittent connectivity drops

[Trizzler]

Hello, I've been experienced repeated and intermittent connectivity drops at my modem.  During the 'outages', my internal network seems to operate fine as I can connect to other devices on the network without issue.

I've noticed many critial errors in the modem's log, as well as what appears to bee poor upstream signal.  I have also noticed that I often only have 1/4 upstream channels locked.  A modem reset will often result in 4/4 upstream channels locked after bootup, but after some time it will drop back down to 1/4.

Below are from the modem logs (Motorola MB7420)

Thanks,

Time	Priority	Description
Mon Jun 01 16:50:50 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:51:23 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:51:30 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:52:03 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:52:10 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:52:43 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:52:50 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:53:22 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 16:53:30 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 17:26:45 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 18:32:04 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 18:32:04 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:33:23 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:33:25 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:35:33 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:36:35 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:37:09 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:39:10 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:39:20 2020	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Mon Jun 01 19:45:48 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:45:49 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:47:58 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:48:13 2020	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Mon Jun 01 19:48:57 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:49:08 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:51:07 2020	Critical (3)	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:51:21 2020	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Mon Jun 01 19:51:40 2020	Warning (5)	Unicast DSID PSN startup error
Mon Jun 01 19:57:08 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:57:09 2020	Critical (3)	Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;
Mon Jun 01 19:57:21 2020	Critical (3)	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:40:96:94;CMTS-MAC=2c:86:d2:89:a3:94;CM-QOS=1.1;CM-VER=3.0;

Startup Sequence

Startup Step Status Comment       Acquire Downstream Channel 591000000 Hz Locked       Upstream Connection OK Operational       Boot State OK Operational       Configuration File OK         Security Enabled BPI+

Connection Status

System Up Time 0 days 00h:37m:24s         Network Access Allowed

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected 1 Locked QAM256 21 591.0 3.7 40.0 6 0 2 Locked QAM256 33 663.0 4.4 39.8 9 0 3 Locked QAM256 22 597.0 5.6 40.3 507 163 4 Locked QAM256 23 603.0 5.2 40.2 491 246 5 Locked QAM256 24 609.0 4.1 40.0 509 150 6 Locked QAM256 25 615.0 3.5 39.8 470 221 7 Locked QAM256 26 621.0 3.3 39.7 516 214 8 Locked QAM256 27 627.0 3.6 39.8 423 305 9 Locked QAM256 28 633.0 4.0 39.8 485 218 10 Locked QAM256 29 639.0 4.2 39.8 515 172 11 Locked QAM256 30 645.0 4.0 39.8 477 208 12 Locked QAM256 31 651.0 3.6 39.7 484 229 13 Locked QAM256 32 657.0 4.0 39.8 461 206 14 Locked QAM256 34 669.0 5.0 39.9 414 420 15 Locked QAM256 35 675.0 5.7 39.5 528 298 16 Locked QAM256 36 681.0 6.1 40.1 471 280 Total             6766 3330

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV) 1 Locked ATDMA 2 5120 36.5 47.5 2 Locked ATDMA 1 5120 30.1 49.2 3 Locked ATDMA 3 5120 17.3 54.0 4 Locked ATDMA 4 5120 23.7 51.0

@ComcastMorgan 

[EG · Accepted solution]

The upstream power is too high. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, 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 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

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.

[Trizzler]

Thanks EG!

I eliminated the only splitter in the line this past weekend, with only slight improvement after doing so.

I did check the connection at the house and the modem for any oxidation, but didn't find any on the coax; but I still made an effort to clean the wire.  I did however notice that where the street drop connects to the house is in a box on the outside of the house.  That connection is made at a grounding block/splicer (not sure the exact term.)  The ground wire was heavily oxidized and a little loose.  I got that cleaned up and tightened, hoping it would help.  There are a couple connections at the street, but I didn't disconnect them to investigate.

Got the modem booted back up and didn't see any new critical errors, but the upstream power still looks high.

The connection is usually the worst between ~16:00 and 20:00, so I will monitor it this eveneing to see if there has been an improvement.  Even if there is an improvement, would it be wise to have a tech investigate the high upstream power and look for a solution?

Here is the current connection data:

Startup Sequence

Startup Step Status Comment       Acquire Downstream Channel 663000000 Hz Locked       Upstream Connection OK Operational       Boot State OK Operational       Configuration File OK         Security Enabled BPI+

Connection Status

System Up Time 0 days 00h:09m:09s         Network Access Allowed

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected 1 Locked QAM256 33 663.0 4.8 39.6 9 0 2 Locked QAM256 21 591.0 4.1 39.7 0 0 3 Locked QAM256 22 597.0 4.9 39.8 2 0 4 Locked QAM256 23 603.0 5.7 40.0 5 0 5 Locked QAM256 24 609.0 4.3 39.7 6 0 6 Locked QAM256 25 615.0 3.7 39.4 4 0 7 Locked QAM256 26 621.0 3.4 39.4 4 0 8 Locked QAM256 27 627.0 3.9 39.5 8 0 9 Locked QAM256 28 633.0 4.0 39.5 6 0 10 Locked QAM256 29 639.0 4.4 39.5 3 0 11 Locked QAM256 30 645.0 4.2 39.6 3 0 12 Locked QAM256 31 651.0 3.9 39.4 7 0 13 Locked QAM256 32 657.0 4.3 39.5 13 0 14 Locked QAM256 34 669.0 5.4 39.8 6 0 15 Locked QAM256 35 675.0 6.1 39.6 6 0 16 Locked QAM256 36 681.0 6.7 40.0 9 0 Total             91 0

Upstream Bonded Channels

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV) 1 Locked ATDMA 3 5120 17.3 54.0 2 Locked ATDMA 1 5120 30.1 47.5 3 Locked ATDMA 2 5120 36.5 45.5 4 Locked ATDMA 4 5120 23.7 50.5

Thanks,

[EG]

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@Trizzler wrote:

 Even if there is an improvement, would it be wise to have a tech investigate the high upstream power and look for a solution?

The goal is to try and get the upstream power on all channels down below 45 dB. 40 to 45 is even better. If it can't be done then certainly yes, get a tech visit. Good luck with it !

[Trizzler]

Thanks EG.

No modem errors in the last 2 days, but the upstream power has still not improved.  I will attempt to get a tech to improve that issue, but for now, everything appears to be at least stable/useable.

Thanks!

[fkcsco817]

The expert response seems inconsistent. First he proposes that excessive high signal can cause intermittent drop outs.  Then he suggests removing excess splitters is the answer. but splitters attenuate the signal not increase them, so if anyhting, perhaps additonal splitters are required?

Honestly, this is a persistent problem that has never been solved by anyone at Xfinity. It's pervasive on the internet and there is not a single satisfacory solution that has been proposed on this or any other forum. It is not an issue specific to the brand of TV or the any other identifiable variable as far as I can tell. In my case, it effects only 1 of 8 TVs in the house, and I've replaced all cable, power supply and X1 boxes feeding the unit to no avail. Techs can't do anyhting since its an intermittent problem. They're stumped, and so is Xfinity tech support. You have a problem and it remains unsolved.  I only wish I could change to another provider but cannot as no others are available in my area. It's a blemish on an otherwise good system. I will probably pull the plug and go Roku.

[EG]

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@fkcsco817 wrote:

First he proposes that excessive high signal can cause intermittent drop outs.  Then he suggests removing excess splitters is the answer. but splitters attenuate the signal not increase them, so if anyhting, perhaps additonal splitters are required?

Splitters decrease the downstream power, and they INCREASE the upstream power......

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[EG]

7 month old dead thread closed.....