Connection dropouts, T4 timeouts. & just one upstream channel

[JayQue2]

Hello there. I too am having timeout issues with green blinking US light, but on a Netgear c7000. It started back in May after maintenance was done in my area. I had this same issue happen to me when i first purchased the modem & was fixed by both a field tech along with a phone rep working together, but the residential techs that come out say the dont do that & blame my modem. Can someone please help? Like i said it's been an issue since 5/2019. Thanks in advance.

[Comcast_Support]

Hi, JayQue2. Thank you for coming here and posting publicly for support. It's frustrating to hear about your intermittent connectivity issues. This is definitely something we can troubleshoot with you. Have you completed any speed tests here: https://speedtest.xfinity.com/? You mentioned the US light flashing on your device, which could indicate a communication problem that may be stemming from signal issues. If it rarely blinks, it just means it's establishing a connection.

Please take a look at this whenever you get a chance: https://forums.xfinity.com/t5/Your-Home-Network/Xfinity-Internet-Connection-Troubleshooting-Tips/m-p... After doing so, can you please post your power levels? These would be the helpful values: Downstream Power Levels, Downstream Signal to Noise Ratio (SNR), Upstream Power Level, Upstream Signal to Noise Ratio (uSNR), Upstream Receive Power. You can also post a screenshot of your event log, if you'd like. We will see what we can do to help form there. Thanks!

[EG]

Adding, have you power-cycled the modem lately ?

[JayQue2]

Here are the requested screenshots. I have power cycled the device which ended with the same results. A customer service rep did notice a second device on my account (should only be one), so she removed both devices then re-provisioned my actual device with same result on my end. FYI: Last residential tech here installed an attenuator which solved the issue momentarily. Original in wall wiring in the home jumps from room to room from outside.

[EG]

Can't see your pics. Since you are a new poster, they need to be approved by a Forum Admin. That could take some time. In the interim, you could try hosting them at one of those free third-party pic hosting sites like Imgur or Photobucket and post the link to them here.

[JayQue2]

They're up now. Thanks again. @EG @Comcast_Support 

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@EG wrote:

Can't see your pics. Since you are a new poster, they need to be approved by a Forum Admin. That could take some time. In the interim, you could try hosting them at one of those free third-party pic hosting sites like Imgur or Photobucket and post the link to them here.

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[JayQue2]

Issue still there after multiple reboots, factory resets & pressing and holding the reset button for 30 seconds. Uncorrectables seem to get fixed upon reboot, but return after a few minutes. Issue happens on both wired & wireless devices. Not sure why techs wont drop a new line to my living room from the box outside my home.., being that the original wiring in the walls is from 2004 & has splitters in rooms that tap into other rooms. Phone reps still say they see timeouts and assure me it is Not my modem. The back & forth is stressful to say the least.

[EG]

Even though the signal stats looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) 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 can check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

[JayQue2]

Thanks again @EG 

[EG]

Quite welcome ! 

[Comcast_Support]

Hey, JayQue2.

Thanks for your patience and for trying to resolve the issue with EG's assistance. We can certainly take a closer look into the issue and see if we can get this figure out. Can you please send us a PM with your first and last name so we may further assist you?

To send a private message, please click the name "Comcast_Support" then select "Send a Message" on the right side.

[JayQue2]

Just an update for the public on the matter. Issue with my Internet is still present. Swapped my Netgear c7000 for a Xfinity issued one for testing purposes and ended up with the same results. Techs can't seem to figure out what the modem event log files, automated phone system AKA modem health check & the Rep on these forums see. The Techs involved are both a Supervisor & a Manager, yet they see no issues on my end. Not sure if anyone can chime in. Any helpful info is greatly appreciated.

[JayQue2]

@JayQue2 wrote:

Just an update for the public on the matter. Issue with my Internet is still present. Swapped my Netgear c7000 for a Xfinity issued one for testing purposes and ended up with the same results. Techs can't seem to figure out what the modem event log files, automated phone system AKA modem health check & the Rep on these forums see. The Techs involved are both a Supervisor & a Manager, yet they see no issues on my end. Not sure if anyone can chime in. Any helpful info is greatly appreciated.

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Update #2. Still no fix. Modem has been monitored for some time now & no one seems to know what's the issue. I was informed the engineering department got involved yet can't figure it out. On a side note. I've had this issue before in the past & was immediately fixed by a savvy phone rep who knew it was not the modem or cabling & got on the phone with the tech & together they fixed it. So I do have hope in this getting fixed. Still waiting for a fix.

[EG]

I'm going to re-escalate your issue..

[JayQue2]

Sounds good @EG . By any chance have you ever seen or heard of what I mentioned? About there being a quick fix involving a phone rep & a tech..? I've seen it once & a follow up install call from Xfinity a few months ago said he knew exactly what was happening & assured me it was not the cabling and/or modem. Said he's worked with modems for years & could fix it with the tech on the line. Unfortunately the tech had already left. So I know there's a fix for sure.

[Comcast_Support]

Hi, JayQue2. Since our Facebook team is working with you on this, they will continue to work with you and provide updates there. They will take the lead on this. Once we have reached a solution with you there, we can summarize everything here and confirm everything has been fixed. Thanks!

[JayQue2]

Same exact issue here. Had it for 8 months now. Still looking into it myself. Please post an update if any. Thanks in advance.

[JayQue2]

Still waiting for a fix on this. Now my bill can't seem to be fixed either after it was changed without my consent in October. What do I do next? What does one do after Comcast stops troubleshooting your Internet because "everything looks good on their end" & can't fix your billing issue that they created? I've been chatting on Facebook for over 6 hours literally repeating myself to different techs who claim to be corporate level techs. Internet issue for a total of 8 months & billing issue for 2 months. What next?

[EG]

I'm going to re-escalate your issue. Standby for a reply.

[JayQue2]

This is what my event log says. This all srarted after maintanance was done in my area. Also happened with a Xfinity provided modem & my neighbors are also having issues. All cables in my home are New per Xfinity. Netgear: " T3 timeouts and "No UCDs Received " is concerning. Has ISP checked the noise on the Upstream/reverse path and confirmed?"

Xfinity: "Everything is in the green." 

2019-12-8, 09:37:43 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:49 Notice (6) Honoring MDD; IP provisioning mode = IPv6 1970-1-1, 00:00:40 Notice (6) WiFi Interface [wl1] set to Channel 161 (Side-Band Channel:N/A) - Reason:INIT 1970-1-1, 00:00:40 Notice (6) WiFi Interface [wl0] set to Channel 11 (Side-Band Channel:N/A) - Reason:INIT 1970-1-1, 00:00:37 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2019-12-7, 17:45:46 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 2019-12-7, 17:27:57 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2019-12-7, 15:02:48 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.0;CM-VER=3.0; 2019-12-7, 15:01:52 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 2019-12-7, 14:50:06 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2019-12-6, 14:36:46 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2019-12-6, 14:22:47 Critical (3) Resetting the cable modem due to docsDevResetNow 2019-12-5, 17:13:27 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:44 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:37 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2019-12-5, 16:59:04 Critical (3) Resetting the cable modem due to docsDevResetNow 2019-12-4, 22:05:49 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:44 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:37 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 2019-12-4, 16:54:27 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.1;CM-VER=3.0; 1970-1-1, 00:00:37 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:03:16 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:03:09 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:03:08 Critical (3) No UCDs Received - Timeout;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:02:51 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:01:38 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:59:dc:79:6b:22;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:01:32 Critical (3) No UCDs Received - Timeout;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:01:11 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:01:10 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:59 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:58 Critical (3) SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:42 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0; 1970-1-1, 00:00:39 Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=2c:30:33:bb:64:c0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;

[JayQue2]

Thought I'd link the Netgear conversation here for reference.

https://community.netgear.com/t5/Cable-Modems-Routers/c7000-T3-T4-timeouts-amp-US-Light-blinking/m-p...

[JayQue2]

It appears Comcast/Xfinity has given up on this matter. I will no longer be receiving support from them per the local Manager tech saying they can't replicate my issue on there end. Now I'm stuck with service that they can't provide/fix & a contract that was modified without my consent. How can an ongoing issue like this not be intervened by a corporate employee? There are cables above ground in the gated community I live in that they wont come bury. They have even cancelled tech visits I scheduled to do so, claiming I was the one that canceled. This is what I've been dealing with. Now all the power has been given to the local team that solely relies on there software/apps for troubleshooting with the answer that everything looks good on their end. LOL. Kinda comedic. So what next? They cant fix my service or my bill & my issue is being ignored. Do I actually have to go through the complaint process through the FCC now?

[EG]

FWIW, I have tried yet another re-escalation today...

[JayQue2]

Thanks for your continuous support on this @EG . I was contacted directly by an Executive Customer Relations Agent recently regarding my issue. Fingers crossed this gets resolved soon.

[EG]

My pleasure !

[JayQue2]

Another month has came & gone with literally nothing being done about my issue. Local techs are of no help. They won't look at neighbors lines unless those neighbors actually complain. Almost a year of this! 2 more months.

[EG]

Oyyyy..... Sorry to hear this but I, as a mere customer can only do so much...

[JayQue2]

Thanks for your continued support! You've been very helpful. Unfortunately I am still having this issue. Also, Comcast has ceased all communication with me & will no longer troubleshoot my service. I guess as long as they get Their money, all is well. Thanks again @EG .