Visitor
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2 Messages
How to access higher tier support for intermittent internet: consecutive T3 timeouts
Been having intermittent Comcast internet for about a month. Usually fails several times in the evenings, sometimes once or twice in the morning.
When it fails, I can no longer ping (192.168.100.1) or connect to the modem's webui from my router, but lights on the modem look normal (as if Comcast up/down are good). Often T3 timeout messages in modem log.
- Thought maybe the issue is with my Zoom 3.0 8x4 modem: Replaced it with brand new Motorola 16x4 modem, EXACTLY the same behavior, so have reverted back to Zoom
- Took a week and an hour on the phone to get a Comcast tech out, he suggested debugging by not using in-house coax but instead connect modem directly to exterior Comcast cable. I've done that, using a single, Comcast-sourced 2-1 splitter and 5' Comcast-sourced coax cable. Rest of the house (TV) is connected to other side of splitter, and through a Comcast-supplied high-pass filter (50MHz).
- Intermittent internet outages are continuing, with corresponding T3 timeouts:
| Mon May 31 12:02:44 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - ... |
| 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=94:fb:b2:a3... |
| Mon May 31 10:56:51 2021 | Critical (3) | Resetting the cable modem due to docsDevResetNow |
| Mon May 31 10:52:11 2021 | Critical (3) | No Ranging Response received - T3 time-out;CM-MAC=94:fb:b2:a3... |
| Mon May 31 10:52:03 2021 | Critical (3) | TFTP Request Retries exceeded, CM unable to register |
| Mon May 31 10:52:03 2021 | Critical (3) | TFTP failed - Request sent - No Response;CM-MAC=94:fb:b2:a3:e... |
| Mon May 31 10:51:04 2021 | Critical (3) | Received Response to Broadcast Maintenance Request, But no Un... |
| Mon May 31 10:46:44 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - ... |
| Mon May 31 10:46:41 2021 | Critical (3) | 16 consecutive T3 timeouts while trying to range on upstream ... |
I think modem levels look ok:
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 32 579000000 Hz 6.9 dBmV 40.3 dB 540 167
2 Locked QAM256 33 585000000 Hz 6.8 dBmV 40.3 dB 498 162
3 Locked QAM256 34 591000000 Hz 6.7 dBmV 39.9 dB 530 145
4 Locked QAM256 35 597000000 Hz 6.5 dBmV 39.9 dB 421 223
5 Locked QAM256 36 603000000 Hz 6.5 dBmV 39.9 dB 480 138
6 Locked QAM256 37 609000000 Hz 6.4 dBmV 39.9 dB 561 82
7 Locked QAM256 38 615000000 Hz 6.5 dBmV 39.9 dB 480 147
8 Locked QAM256 39 621000000 Hz 6.4 dBmV 39.9 dB 438 214
Total Correctables Total Uncorrectables
3948 1278
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 7 5120 Ksym/sec 22800000 Hz 40.3 dBmV
2 Locked ATDMA 9 5120 Ksym/sec 35600000 Hz 40.5 dBmV
3 Locked ATDMA 6 5120 Ksym/sec 16400000 Hz 40.0 dBmV
4 Locked ATDMA 8 5120 Ksym/sec 29200000 Hz 40.5 dBmV
Pretty sure my ASUS router is not the issue; its logs have nothing unusual when the internet goes out other than some DHCP renewals. I also notice a flicker of bad video quality on our TV when the internet goes out.
Already wasted hours on the phone. After making an appointment, I get texts, automated voice mail, and humans calling: "We fixed a problem in your area, your problem should be resolved". Internet still dropping. Yeah I get it Comcast, you don't want to roll a truck. Now waiting for the 2nd appt: Me: Appt in 8 days? I'm trying to work at home! Agent: don't worry sir, we'll add you to a wait list. Subsequent Text: Wait-list not available!
Don't get me started how one agent asks if I've been keeping my family safe during the Pandemic... Does she really want to hear about a cousin that died?
Any help is appreciated in getting Comcast to take this seriously.
EG
Expert
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118.4K Messages
5 years ago
The signal stats are o/k but the error log entries indicate that something is going on. Perhaps there is intermittent noise ingress into the line(s) / an upstream channel-return path impairment somewhere.
There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.
I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !
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XfinityBillie
Official Employee
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4.2K Messages
5 years ago
Hello and thank you for taking the time to reach out to us here on our Xfinity Forums. I would love to take a look at the signals here on our end and help you find a resolution. We truly appreciate your business and want you to be able to enjoy your services. Please send us a private message with your name and service address to Xfinity Support by clicking the chat icon at the top right of the page.
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ruebee
New Poster
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22 Messages
5 years ago
Any updates? We're having a similar issue.
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