Xfinity Internet Service Degraded, Unstable After "Network Enhancements In My Area" On March 30th

SUMMARY OF ISSUE:

(1) I had stable, error-free cable internet service until a recent "neighborhood upgrade" on March 30", when the "upgrade" work caused service to be out for a whole day.

(2) Now, our service logs tens of thousands of uncorrected errors per day across sixteen downstream channels, and is not stable, typically disconnecting several times in each 24 hour period.

(3) Neither our equipment or the single run of cable from the Xfinity demarcation point outside our home to the cable modem has been altered in any way from its formerly working (before "neighborhood upgrade") configuration to the current degraded, unstable configuration.

Given these facts, Xfinity's changes to their system during the "neighborhood upgrade" are very strongly implicated in the problems which I am now requesting they remedy. To convince Xfinity that there is a problem with their system and not mine, I have gathered and report here detailed evidence.

BACKGROUND:

I did not have any cable-based service at this property since I bought it decades ago, but in the last few years have needed additional bandwidth due to increased telework/telecommuting opportunities, as well as a virtually mandatory shift to streaming video services. So I reluctantly switched from my 100% reliable (but slow) DSL internet connection to "Xfinity" cable-based service a few years ago, at which time the company installed a new cable drop (since storms had long ago taken down the old one the previous owners used).

From the start my Xfinity internet service worked well, and was stable for months of up-time without interruption. I never had cable television service, so there are no complications to my internal connection:  a single cable runs from the Xfinity connection point at the side of my home directly to a wall plate, connected to a Motorola MB-7420 cable modem.

There are no intervening splitters and/or additional cable runs or amplifiers, and none of my equipment or connections have been altered since the system was stable, (before the Xfinity upgrade work).

A note regarding my background is perhaps relevant: I have degrees in electrical engineering and computer science, and work as a consultant in the field of embedded systems, writing firmware for networking equipment and Ethernet switch gear.

So my complaint here comes from a fairly complete understanding of the basic operation of cable internet systems, having nothing to do with my internal network architecture, routers, switches, WiFi access points and WiFi signal conditions in my home, or anything else that lies beyond Xfinity's system and control.

It only regards Xfinity's responsibility to provide a stable, continuous connection at the cable modem itself.

As I did not change or alter the single cable that runs from Xfinity's feed to my cable modem, and the signal quality problems are all evident at the modem itself,  the strongest possible indication that problems with my connection are related to recent changes made by Xfinity in my neighborhood exists.

I am bringing the problem to the attention of this forum because, although the connection still "works" and a cursory check with the Xfiniity "App" or web site will indicates that it is ostensibly "OK", it is no longer stable nor reliable - the connection quality has degraded.

An intermittent connection that drops out several times per day (or even per week) is simply not acceptable, given the nature of my work.

BRIEF HISTORY:

Initially, my Xfinity connection was as reliable as my former rock-solid DSL service was, which was an unexpected and pleasant surprise.

When I first subscribed to Xfinity Internet, I selected a Zoom 5341 cable modem specifically due to its reputation for stability, reliability and trouble-free operation. And both it and the Xfinity service were indeed reliable and trouble-free for a couple of years.

However in January, Xfinity notified me that I would be forced to replace my perfectly functional and trusted Zoom 5341 cable modem with something else by March 13, or I would lose my service, due to an "expired certificate" in the modem.

A brief digression: for those who don't know what a "certificate" is, it is just a cryptographic key set consisting of a "public" and "private" key ("keys" are just big numbers). "Certificates" have "expiration dates", but in a lot of contexts (like in a cable modem or gateway) those dates can be safely ignored, because numbers don't really "expire" and a certificate's date can't affect the security of a cryptographic exchange unless a certificate's private key was actually compromised. Expiration dates are only included in certificates as a caution, so that if a certificate is compromised, it will eventually "age out" of any systems that are unaware it has been compromised and/or "revoked."

At any rate, I selected another top-rated, Xfinity-approved modem - a Motorola MB-7420 - and installed and activated it around March 12 to avoid any service interruption. And initially, the connection to the new cable modem was as reliable as it had been with the previous Zoom unit.

However, I soon received yet another notice from Xfinity on March 29 that they would be "working to enhance the network in my area" starting March 30", and that the system outage would likely last all day.

The outage did indeed last all day, making it difficult to work, and when I got a message that my service should be back on-line at 7:43 PM, initially the connection quality looked OK. (I had to solve another problem caused by some unannounced changes to Xfinity's gateway servers, but that issue was on my side of the network downstream from the modem, and therefore my responsibility to troubleshoot and correct).

Unfortunately, over the last couple of weeks it has become clear that my connection was somehow degraded during the "upgrade", and it is no longer stable or reliable.

That fact is proven by examining the cable modem error logs, where connection problems are recorded and time-stamped. Here, the logs indicate several cable modem reboots (and commensurate internet connection interruptions) due to poor cable signal quality over a single weekend:

Thursday, April 20   8:30 PM

Friday,   April 21  12:51 AM
Friday,   April 21   5:57 AM
Friday,   April 21   5:58 AM
Friday,   April 21   6:09 AM
Friday,   April 21   8:08 AM
Friday    April 21   7:16 PM
Friday    April 21   9:09 PM

Saturday  April 22   4:04 PM
Saturday  April 22   4:37 PM

Sunday    April 23   3:37 AM
Sunday    April 23  12:28 PM
Sunday    April 23  12:31 PM

In addition, the modem status page shows 171,960 corrected and 105,762 total uncorrected errors on 16 downstream channels over 160 hours (9,600 minutes) of up-time, or approximately 11 uncorrected errors per minute. (Detailed error log messages follow).

Considering that all the easy remedies ("reboot/disconnect/power-cycle the modem) have already been done many times, and that:

   -> Before Xfinity's changes to "enhance" the network in my neighborhood per their March 30th notice, my connection was stable and consistent.

   -> After Xfinity's "enhancements", my connection is no longer stable or consistent.

Xfinity has clearly created a problem that must lie somewhere within Xfinity's system and/or its connection to my home, which only Xfinity can rectify. This assertion is strongly supported by the fact that neither my equipment or cable was changed  when the quality of my formerly reliable service declined.

The ONLY changes made were Xfinity's, outside of my home and my control, and the degradation of my service exactly coincided with the date that Xfinity's "neighborhood system upgrade" was performed.

NEXT STEPS ?

Incidentally, I just received notice from Xfinity that there will be another service interruption tomorrow, Monday April 24th in my area, to "correct performance issues."

While by chance this maintenance operation may remedy the problems I've observed and documented here, I don't want to just rely on luck at this point. I've already wasted far too much time trying to obtain and keep basic, reliable Internet service from Xfinity.

So given the facts and  history I have provided, how can I get Xfinity to restore my service to its former, reliable state without an endless argument about whose equipment is at fault, instructions to repeatedly reboot and/or re-purchase equipment, etc. ?

As a professional, any service that drops packets and disconnects several times per day or week like the service Xfinity is currently providing is simply unacceptable and useless to me. And dealing with the equipment changes, upgrades and other problems Xfinity caused has been incredibly time-consuming, costly and inconvenient as well.

I need a direct path forward to a solution, not more useless, scripted Tier 1 instructions from offshore customer service agents.


[ Modem error logs showing repeated T3/T4 time-outs and attendant connection losses (14 incidents) follow. ]

Thu Apr 20 20:29:01 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Thu Apr 20 20:30:06 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Thu Apr 20 20:30:38 2023   Critical (3)  No Ranging Response received - T3 time-out;
Thu Apr 20 20:31:11 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 00:50:22 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 00:51:27 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Fri Apr 21 00:51:51 2023   Critical (3)  No Ranging Response received - T3 time-out;
Fri Apr 21 00:51:59 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 05:57:24 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 05:57:24 2023   Critical (3)  Unicast Maintenance Ranging attempted - No response - Retries exhausted;
Fri Apr 21 05:57:24 2023   Critical (3)  16 consecutive T3 timeouts while trying to range on upstream channel 1;
Fri Apr 21 05:57:24 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 05:57:24 2023   Critical (3)  Unicast Maintenance Ranging attempted - No response - Retries exhausted;
Fri Apr 21 05:57:24 2023   Critical (3)  16 consecutive T3 timeouts while trying to range on upstream channel 3;
Fri Apr 21 05:57:36 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 05:58:14 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 05:58:15 2023   Critical (3)  DHCP failed - DHCP Solicit sent, No DHCP Advertise received;
Fri Apr 21 05:58:33 2023   Critical (3)  No Ranging Response received - T3 time-out;
Fri Apr 21 05:58:38 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 06:07:59 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 06:09:04 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Fri Apr 21 06:09:19 2023   Critical (3)  No Ranging Response received - T3 time-out;
Fri Apr 21 06:09:40 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 08:07:19 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 08:08:24 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Fri Apr 21 08:08:36 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 12:12:44 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 12:12:58 2023   Warning (5)  Dynamic Range Window violation 
Fri Apr 21 12:13:20 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Fri Apr 21 19:14:31 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 19:15:36 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Fri Apr 21 19:15:55 2023   Critical (3)  No Ranging Response received - T3 time-out;
Fri Apr 21 19:16:10 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Fri Apr 21 21:07:52 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Fri Apr 21 21:08:57 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Fri Apr 21 21:09:19 2023   Critical (3)  No Ranging Response received - T3 time-out;
Fri Apr 21 21:09:26 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Sat Apr 22 16:03:02 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Sat Apr 22 16:04:07 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Sat Apr 22 16:04:21 2023   Critical (3)  No Ranging Response received - T3 time-out;
Sat Apr 22 16:04:45 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Sat Apr 22 16:35:57 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Sat Apr 22 16:37:02 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Sat Apr 22 16:37:28 2023   Critical (3)  No Ranging Response received - T3 time-out;
Sat Apr 22 16:37:35 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Sat Apr 22 16:37:51 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Sat Apr 22 16:37:52 2023   Critical (3)  DHCP failed - RS sent, no RA received;
Sat Apr 22 16:38:04 2023   Critical (3)  No Ranging Response received - T3 time-out;
Sat Apr 22 16:38:26 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Sun Apr 23 03:36:23 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Sun Apr 23 03:37:28 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Sun Apr 23 03:37:46 2023   Critical (3)  No Ranging Response received - T3 time-out;
Sun Apr 23 03:37:54 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Sun Apr 23 12:26:55 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Sun Apr 23 12:28:00 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Sun Apr 23 12:28:12 2023   Critical (3)  No Ranging Response received - T3 time-out;
Sun Apr 23 12:28:16 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

Sun Apr 23 12:30:21 2023   Critical (3)  Started Unicast Maintenance Ranging - No Response received - T3 time-out;
Sun Apr 23 12:31:26 2023   Critical (3)  Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
Sun Apr 23 12:31:38 2023   Notice (6)  Honoring MDD; IP provisioning mode = IPv6 

[ END OF LOG ]