U

Visitor

 • 

12 Messages

Sat, Oct 2, 2021 2:17 PM

Intermittent disconnects and packet loss

I have been having packet loss and disruption of service that leads to frequent disconnects in everything from video calls to streaming to gaming. This issue has been occurring for roughly one month, but was not an issue before. The disconnects happen on all devices connected to the internet. I have gone through the troubleshooting steps, replaced router, modem and all cables, and I have already gone through the chat service and had a comcast maintenance person come out twice (they were not happy to come out the second time and extremely dismissive of my issue). The signal coming to the modem is good, which I knew already and is the only thing they check.

I have been tracking latency and packet loss with pingplotter and it is clear that there are spikes of packet loss occurring even when nobody is at home, or everyone is asleep. I have a hard time believing that this is a bandwidth or a data issue when this program is the only thing running. Looking at the nodes, it appears the packet loss is occurring at a particular IP (96.110.235.69) that is well upstream of the modem/router on site. I need to talk with a network specialist who will take my issue seriously.

This post was escalated on October 10, 2021 by EG

Responses

BruceW

Gold Problem Solver

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22.9K Messages

15 d ago

Please post a trace to a host that has the troublesome IP along the route.

Visitor

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12 Messages

14 d ago

The top trace is to 96.110.235.69, the bottom trace is to google. The disconnects with google are highly correlated with packet loss further upstream. The overall packet loss to 96.110.235.69 is ~5% where to my router it is less than .1%.
Here is the zoom in of the route since the image uploaded at a low resolution:  https://ibb.co/BKVz3hP

(edited)

BruceW

Gold Problem Solver

 • 

22.9K Messages

14 d ago

(Your post will be visible once Comcast approves the image it contains. See https://forums.xfinity.com/conversations/getting-started/disappearing-forum-posts/606894c37437b81d05b7b638?commentId=606b25cb322c887da0f3c0a2.)

The image resolution is so low that I can't see it very well, but as best I can tell the trace continues past the hop you highlighted and reaches the destination with little packet loss, so the apparent loss at the intermediate hops is probably not significant. Please see https://www.dslreports.com/faq/14068.

Are you connecting via Wifi or Ethernet? If Wifi, it's best to switch to an Ethernet cable connection if possible for testing.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you still need help, please post your Internet plan speed and the following information from your modem or gateway:

  • model number
  • downstream power levels and SNR
  • upstream power levels
  • event log, if available (Be sure to remove or blot out any MAC addresses. Forum security processing considers them "personal information" and may prevent the event log from posting if these are present.)

(edited)

Visitor

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12 Messages

14 d ago

I am using a NetGear CM600 modem (serial number 4DF597WEA04DD). I am connected via ethernet with a 100 Mbps plan. I have also tested it with a different modem / router combo to no avail. 

Downstream power levels:

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 17 519000000 Hz 8.6 dBmV 40.5 dB 0 0
2 Locked QAM256 1 393000000 Hz 6.6 dBmV 39.9 dB 0 0
3 Locked QAM256 2 399000000 Hz 6.8 dBmV 39.9 dB 0 0
4 Locked QAM256 3 405000000 Hz 6.9 dBmV 40.0 dB 0 0
5 Locked QAM256 4 411000000 Hz 6.6 dBmV 39.8 dB 0 0
6 Locked QAM256 5 429000000 Hz 7.2 dBmV 40.1 dB 0 0
7 Locked QAM256 6 435000000 Hz 7.1 dBmV 40.1 dB 0 0
8 Locked QAM256 7 441000000 Hz 7.3 dBmV 40.1 dB 0 0
9 Locked QAM256 8 447000000 Hz 7.2 dBmV 40.0 dB 0 0
10 Locked QAM256 9 453000000 Hz 7.3 dBmV 40.1 dB 0 0
11 Locked QAM256 10 459000000 Hz 7.2 dBmV 40.1 dB 0 0
12 Locked QAM256 11 465000000 Hz 7.4 dBmV 40.1 dB 0 0
13 Locked QAM256 12 471000000 Hz 7.6 dBmV 40.2 dB 0 0
14 Locked QAM256 13 477000000 Hz 7.6 dBmV 40.2 dB 0 0
15 Locked QAM256 14 483000000 Hz 8.0 dBmV 40.3 dB 0 0
16 Locked QAM256 15 489000000 Hz 7.9 dBmV 40.2 dB 0 0
17 Locked QAM256 16 495000000 Hz 7.9 dBmV 40.9 dB 0 0
18 Locked QAM256 18 525000000 Hz 8.4 dBmV 40.9 dB 0 0
19 Locked QAM256 19 531000000 Hz 8.6 dBmV 41.3 dB 0 0
20 Locked QAM256 20 537000000 Hz 8.8 dBmV 41.4 dB 0 0
21 Locked QAM256 21 543000000 Hz 8.9 dBmV 41.3 dB 0 0
22 Locked QAM256 22 549000000 Hz 8.8 dBmV 41.4 dB 0 0
23 Locked QAM256 23 555000000 Hz 8.6 dBmV 41.2 dB 0 0
24 Locked QAM256 24 561000000 Hz 9.0 dBmV 41.4 dB 0 0

Upstream power levels:

Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 93 5120 Ksym/sec 36500000 Hz 41.0 dBmV
2 Locked ATDMA 95 5120 Ksym/sec 23700000 Hz 40.0 dBmV
3 Locked ATDMA 96 5120 Ksym/sec 17300000 Hz 39.5 dBmV
4 Locked ATDMA 94 5120 Ksym/sec 30100000 Hz 40.3 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

Event log with Mac Addresses censored:

2021-10-02, 09:01:28 Notice (6) Honoring MDD; IP provisioning mode = IPv6
2021-10-02, 09:01:12 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 09:00:00 Warning (5) MDD message timeout;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:59:57 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:59:56 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:59:51 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:59:50 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:57:26 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:57:26 Warning (5) MDD message timeout;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:57:19 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-10-02, 08:57:19 Warning (5) MDD message timeout;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-30, 09:21:01 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-30, 08:20:06 Critical (3) Resetting the cable modem due to docsDevResetNow
2021-09-28, 12:57:05 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 12:57:04 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 12:56:42 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 12:56:33 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 12:56:16 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 12:50:52 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 11:42:20 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-28, 11:18:08 Critical (3) Resetting the cable modem due to docsDevResetNow
2021-09-27, 15:59:10 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:59:07 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:59:03 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:58:46 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:58:01 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;
2021-09-27, 15:57:55 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;
2021-09-27, 15:57:48 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:56:01 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2021-09-27, 15:54:01 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=XXX;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2021-09-27, 15:53:58 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:53:58 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:53:20 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:53:19 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
2021-09-27, 15:53:02 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=XXX;CMTS-MAC=XXXXX;CM-QOS=1.0;CM-VER=3.0;

Here is an example of packet loss starting from a comcast node going to google: https://imgur.com/a/tVoSxq3

(edited)

BruceW

Gold Problem Solver

 • 

22.9K Messages

14 d ago

Thank you for the updated image, but my interpretation is the same: the apparent packet loss and latency is most likely due to the routers at intermediate hops assigning low priority to responses to trace packets. If they were were actually dropping packets or delaying them you would see that in all the subsequent hops.

If you could supply the information requested above we might have a better idea what's going on.

Visitor

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12 Messages

I have provided the upstream and downstream power levels, the event log, and an example of all subsequent packets being lost.

BruceW

Gold Problem Solver

 • 

22.9K Messages

13 d ago

Your latest PingPlotter image appears to show 96.7% packet loss beginning at the 3rd Comcast hop and continuing on into Google's 1e100 network. The downstream power level to your modem is a little high, but I doubt if it's high enough to be causing this.

The error log has a number of entries that suggest it is having trouble communicating with Comcast's network. Although the stats posted look OK, there are other signal stats that the modem doesn't report. So we don't really know if there is a problem at Comcast, or if there is an intermittent connection between their network and your modem.

I'd suggest having the premise techs back out for another look. If you don't want to do that, the "contact me" link on https://www.xfinity.com/hub/customer-experience/xfinity-customer-care-update might be worth a try. Be aware that replies from that office vary from extremely helpful to nonsensical.

Visitor

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1 Message

13 d ago

I am having something similar happen as well. It's like the internet is constantly blinking, the signal goes from strong to choppy within seconds constantly. It only started in the last 2 weeks. Sometimes my devices can't find the internet at all. Speed test show either great bandwidth or it can't complete the test. I have a modem + route from Xfinity and haven't done any of my own tests yet.

EG

Expert

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89.6K Messages

13 d ago

@audly_speedy 

Please create a new topic of your own here on this board detailing your issue and I will attempt to assist you there. Please do not hijack someone else's help thread in progress. Multiple posters piling on to and being helped in a single thread becomes too complicated. confusing, and convoluted. And it's unfair to the original poster. Thank you. 

Visitor

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12 Messages

13 d ago

Are the modem errors suggesting that there is a problem with the modem itself, or just with its connection to the network? The modem is less than 2 weeks old and one that is recommended by Comcast, so I'd hope that it is functional.

I'm not willing to have another tech out here again at this point. I've been burned by them showing up for 5 minutes, saying everything looks good, and charging me 100 bucks, so I'd like to do what I can myself. In any case, I have yet another set of coax cables coming that I'll try out, as well as a 3rd modem. I'll try the "contact me" page and see where that gets me. I'm not really sure what else to try beyond that except for a different internet plan that might route my traffic differently.

BruceW

Gold Problem Solver

 • 

22.9K Messages

13 d ago

Although it's possible for the errors a modem reports to indicate a problem with the modem, they are much more likely to be caused by weak or noisy network signals or a poor connection to the network.

Visitor

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12 Messages

8 d ago

UPDATE: I replaced my modem with one that Comcast sent, tried switching to a 400 Mbps plan, and replaced coax cable again. If anything the problem is worse. Are frequent disconnects just to be expected with Comcast service? Interestingly the one thing that I tried that did work was using a mobile hotspot to connect to the internet. I feel like I am out of options in trying to work with Comcast to resolve this issue.

Visitor

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12 Messages

8 d ago

It seems that I am not getting a good connection with the Comcast servers(?). This occurs 1-2 times per hour. https://imgur.com/hPsuJWT

BruceW

Gold Problem Solver

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22.9K Messages

8 d ago

@user_23a836 wrote: "... This occurs 1-2 times per hour. ..."

The only advice I can offer is keep leaning on them until they fix this.

Visitor

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12 Messages

7 d ago

Is there a way to get a Comcast rep's eyes on this issue? Explaining the problem half a dozen times over chat / phone only for them to reset my modem is quite discouraging. If I could direct them to this thread they might have a better idea of what's going on.

Official Employee

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180 Messages

Hey there, happy to look into this further for you. Send a direct message to Xfinity Support with your name and address please. 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick
EG

Expert

 • 

89.6K Messages

7 d ago

@user_23a836  I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. You should get a reply here in your topic. Good luck !

(edited)

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