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Sunday, June 9th, 2024 4:48 PM

Closed

Frequent Connection Drops and Uncorrected Errors on 3/33 Channels (Suspected Noise on Line)

We are experiencing frequent "blips" where the internet drops out at our condo and comes back online after a brief 1-5 minute period.

Previously, we had similar problems and a tech was able to trace the line and determine that someone had fitted a dampener on our connection to the main junction box in the condo building. At that time, he confirmed that our coax layout (all cables, connections, and in-line splitters) were delivering the expected signal to the modem but the presence of the dampener was causing issues due to the artificial ceiling on the signal frequency. For a time afterwards, the connection worked flawlessly. However, for the past month (or maybe a little more), we are again experiencing issues staying connected consistently and this is confirmed in the modem event logs.

Specifically, we see  large numbers of uncorrected errors on 3 channels (including the OFDM PLC channel):

 Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked QAM256 20 567.0 4.8 43.4 15 0
   2 Locked QAM256 1 453.0 6.5 45.1 16 0
   3 Locked QAM256 2 459.0 6.5 45.0 690 2593
   4 Locked QAM256 3 465.0 6.4 44.8 1058 2821
   5 Locked QAM256 4 471.0 6.2 44.7 31 0
   6 Locked QAM256 5 477.0 6.3 44.8 20 0
   7 Locked QAM256 6 483.0 6.4 44.9 1 0
   8 Locked QAM256 7 489.0 6.7 44.8 11 0
   9 Locked QAM256 8 495.0 6.5 44.9 27 0
   10 Locked QAM256 9 501.0 6.6 44.8 26 0
   11 Locked QAM256 10 507.0 6.3 44.8 11 0
   12 Locked QAM256 11 513.0 5.8 44.3 1 0
   13 Locked QAM256 12 519.0 5.7 44.4 11 0
   14 Locked QAM256 13 525.0 5.6 44.2 16 0
   15 Locked QAM256 14 531.0 5.1 44.0 12 0
   16 Locked QAM256 15 537.0 4.7 43.5 2 0
   17 Locked QAM256 16 543.0 5.2 44.0 4 0
   18 Locked QAM256 17 549.0 4.9 43.6 2 0
   19 Locked QAM256 18 555.0 5.2 43.6 1 0
   20 Locked QAM256 19 561.0 5.3 43.8 13 0
   21 Locked QAM256 21 573.0 4.6 43.4 19 0
   22 Locked QAM256 22 579.0 4.2 43.0 7 0
   23 Locked QAM256 23 585.0 4.4 43.1 6 0
   24 Locked QAM256 24 591.0 3.9 42.9 20 0
   25 Locked QAM256 25 597.0 4.4 43.0 16 0
   26 Locked QAM256 26 603.0 3.9 42.7 26 0
   27 Locked QAM256 27 609.0 4.3 43.0 17 0
   28 Locked QAM256 28 615.0 3.7 42.6 10 0
   29 Locked QAM256 29 621.0 3.9 42.7 3 0
   30 Locked QAM256 30 627.0 3.9 42.6 3 0
   31 Locked QAM256 31 633.0 3.6 42.5 1 0
   32 Locked QAM256 32 639.0 4.0 42.8 65 0
   33 Locked OFDM PLC 193 957.0 -0.7 38.9 -1740062231

1709408452

Note, this is for a reported System Up Time of `25 days 01h:00m:09s`

Additionally, we see a number of errors that seem to indicate the OFDM PLC channel is operating outside of the expected bounds. For example, here is the event log for a recent failure on the OFDM PLC channel:

Time  Priority  Description 
07:47:20
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 1 2 3.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
07:47:22
Tue Jun 4 2024
Warning (5) MDD message timeout;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
07:47:23
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 21; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
07:47:46
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 4; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
07:49:02
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 22; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
07:49:02
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 1 2 3.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
07:49:51
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 23; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;

Similarly, here is a recent event log for a failure on Channel ID 2:

Time  Priority  Description 
09:28:54
Tue Jun 4 2024
Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 2 3; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;

I also see a number of other warnings and errors unrelated to any particular channels:

Time Priority Description
01:14:04
Thu Jun 6 2024
Warning (5) MDD message timeout;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:14:47
Thu Jun 6 2024
Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:14:55
Thu Jun 6 2024
Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:14:56
Thu Jun 6 2024
Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:14:57
Thu Jun 6 2024
Critical (3) No Maintenance Broadcasts for Ranging opportunities received - T2 time-out;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:14:57
Thu Jun 6 2024
Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:15:48
Thu Jun 6 2024
Warning (5) Lost MDD Timeout;CM-MAC=XXXX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
01:18:31
Thu Jun 6 2024
Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
01:19:09
Thu Jun 6 2024
Warning (5) Lost MDD Timeout;CM-MAC=XXXX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
01:19:18
Thu Jun 6 2024
Critical (3) UCD invalid or channel unusable;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:20:03
Thu Jun 6 2024
Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:20:13
Thu Jun 6 2024
Notice (6) Honoring MDD; IP provisioning mode = IPv6
01:20:50
Thu Jun 6 2024
Critical (3) DHCP failed - DHCP Solicit sent, No DHCP Advertise received;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:23:34
Thu Jun 6 2024
Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=XXXX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
01:23:36
Thu Jun 6 2024
Critical (3) UCD invalid or channel unusable;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:23:40
Thu Jun 6 2024
Notice (6) Honoring MDD; IP provisioning mode = IPv6
01:24:48
Thu Jun 6 2024
Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;
01:24:54
Thu Jun 6 2024
Critical (3) UCD invalid or channel unusable;CM-MAC=XXXX;CMTS-MAC=XXXX;CM-QOS=1.1;CM-VER=3.1;

All this leads me to suspect there is some noise on the line but I have no idea how to proceed to get it fixed. Please advise.

Retired Employee

 • 

1.5K Messages

1 year ago

Hello @evilsnoopi3, thank you for taking the time to reach out on social media.  I understand your concern with the internet, and I'd like the opportunity to check into that for you.

 

To access your account, will you please send us a direct message with your full name and complete service address.

 

To do so, click on the chat icon located at the top right of this forums page.

Here's the detailed steps to direct message us:

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  • Press Enter to send your message

Expert

 • 

110.9K Messages

1 year ago

@evilsnoopi3 @XfinityKrista 

Please circle back here and post any possible solutions for the issue here in these open forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.

3 Messages

1 year ago

I reached out in a DM and was asked to provide my service address, whether I had any mesh devices, and if I have a separate router from my modem. I confirmed that I do have a separate modem and router and that the router is a mesh system (modem: MB8611, router/mesh system: AX6600). I also informed support that the blips were not limited to wifi and also occurred on wired devices.

Support confirmed "one of your signals is out of spec" and are sending a technician. I will report back if I get more information from the tech.

(edited)

Expert

 • 

110.9K Messages

1 year ago

@evilsnoopi3 

Thanks for the update ! Good luck with it !

3 Messages

1 year ago

Walked the line with the tech. We made a couple of changes to the incoming cable topography with the hopes that it would resolve the issue:

1. We removed an old splitter and connected the feeder line directly to the line leading to my modem as it is the only cable connected device in my home. The tech observed that the splitter could cause noise in two ways: from the rust/age-related degradation and from having a connected, uncapped, unused line.
2. We replaced the filter/line connector which sat between the line coming from the main tap and my condo's cabling. This was more precautionary according to the tech but he did note that the filter/line connector was an older model.
3. We capped the final, open port on the main tap (8 way tap for a condo with 7 units; we capped the 8th); according to the tech this could also be a source of noise.

After all those changes were made I see significant improvement on the Pwr (dBmV) readings for all channels (for example, the OFDM PLC channel went from -0.7 to 2.6 and channels 2 & 3 are now at 10.5 and 10.7 respectively). I will be monitoring the network performance now to determine if this resolves the issue. The tech did indicate the next step if the problem continues would be to replace the cabling for each leg.

Expert

 • 

110.9K Messages

1 year ago

Thanks for the latest ! Hope that stuff does it !!

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