U

Visitor

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10 Messages

Tue, May 24, 2022 1:22 AM

T3 and t4 timeouts

My internet signal is great 98% of the time but then out of the blue I get a bunch of t3 and t4 timeouts.  A tech came out and said all the wiring in the house was good and the signal was great.  Another tech came out to look at the pedestal and said it was fine as well.  One person I talked to on the phone said that the signal was weird and it was definitely an issue on Comcast’s end.  Then another person on the phone today said that the timeouts were the modems or routers fault.  I don’t understand how a separate router can cause a timeout on the modem.  Unless I’m crazy I don’t think they can, which doesn’t make me trust the comcast person that told me.  Anyway, I’ve replaced my modem and have the same issues.  Current modem is a mb7420.  There have been 4 t4 timeouts over the past couple of days.   Internet is great other than the timeouts though.   Can anyone please provide some insight?

EG

Expert

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94.3K Messages

1分前

Are you actually experiencing any connectivity problems / dropouts, or are you just focusing on those error log entries ?

Visitor

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10 Messages

1分前

 I’m losing connectivity.  Internet goes out for 5 minutes or so each time.  It happened a few times last night.

EG

Expert

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94.3K Messages

1分前

What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1

Or use the method here: https://www.192-168-1-1-ip.co/router/motorola/mb7420/4445/ 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

Visitor

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10 Messages

1分前

Startup Sequence    
   Startup Step Status Comment

  
   Acquire Downstream Channel 405000000 Hz Locked
  
   Upstream Connection OK Operational
  
   Boot State OK Operational

  
   Configuration File OK
  
   Security Enabled BPI+
  


   Connection Status    
   System Up Time 1 days 00h:15m:06s  
  
   Network Access Allowed  
  


   Downstream Bonded Channels  
  
   Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
1 Locked QAM256 42 405.0 4.9 38.9 17 73
2 Locked QAM256 43 411.0 4.7 38.9 0 0
3 Locked QAM256 44 417.0 4.5 38.8 0 0
4 Locked QAM256 45 423.0 4.4 38.8 0 0
5 Locked QAM256 1 435.0 4.2 38.8 0 0
6 Locked QAM256 2 441.0 4.2 38.8 0 0
7 Locked QAM256 3 447.0 4.1 38.8 0 0
8 Locked QAM256 4 453.0 3.9 38.7 0 0
9 Locked QAM256 5 459.0 3.8 38.6 0 0
10 Locked QAM256 6 465.0 3.6 38.5 0 0
11 Locked QAM256 7 471.0 3.6 38.5 0 0
12 Locked QAM256 8 477.0 3.9 38.7 0 0
13 Locked QAM256 9 483.0 4.5 39.0 0 0
14 Locked QAM256 10 489.0 4.5 39.0 0 0
15 Locked QAM256 11 495.0 4.4 39.0 0 0
16 Locked QAM256 12 501.0 4.4 39.1 0 0
Total             17 73


   Upstream Bonded Channels  
  
   Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked ATDMA 3 5120 22.8 35.5
2 Locked ATDMA 1 5120 35.6 36.3
3 Locked ATDMA 4 5120 16.4 36.3
4 Locked ATDMA 2 5120 29.2 36.0



EG

Expert

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94.3K Messages

1分前

The signal stats looked good / in spec at that snapshot in time. Please also post those error log entries as well in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. Personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

Visitor

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10 Messages

1分前

Working on getting the logs now.  I’m not sure if this would matter or not, but according to xfinitys outage map, they think I’m a different place than I really am. I have an address that comes up as 2 different locations for some reason in Google maps.  Could this cause a signal issue?

Visitor

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10 Messages

1分前

Mon May 23 23:41:36 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Mon May 23 23:41:43 2022        Notice (6)            Honoring MDD; IP provisioning mode = IPv6

Wed May 25 18:39:49 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 18:39:49 2022        Critical (3)           Unicast Maintenance Ranging attempted - No response - Retries exhausted;

Wed May 25 18:39:49 2022        Critical (3)           16 consecutive T3 timeouts while trying to range on upstream channel 1

Wed May 25 18:40:02 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 18:40:02 2022        Critical (3)           Unicast Maintenance Ranging attempted - No response - Retries exhausted;

Wed May 25 18:40:02 2022        Critical (3)           16 consecutive T3 timeouts while trying to range on upstream channel 3;

Wed May 25 18:40:09 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 18:40:09 2022        Critical (3)           Unicast Maintenance Ranging attempted - No response - Retries exhausted;

Wed May 25 18:40:09 2022        Critical (3)           16 consecutive T3 timeouts while trying to range on upstream channel 0;

Wed May 25 18:40:52 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 18:45:12 2022        Critical (3)           Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;

Wed May 25 18:45:24 2022        Notice (6)            Honoring MDD; IP provisioning mode = IPv6

Wed May 25 18:53:57 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 18:58:17 2022        Critical (3)           Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;

Wed May 25 18:58:27 2022        Critical (3)           No Ranging Response received - T3 time-out;

Wed May 25 18:58:40 2022        Notice (6)            Honoring MDD; IP provisioning mode = IPv6

Wed May 25 19:01:53 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 19:06:13 2022        Critical (3)           Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;

Wed May 25 19:06:23 2022        Critical (3)           No Ranging Response received - T3 time-out;

Wed May 25 19:06:28 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 19:06:35 2022        Notice (6)            Honoring MDD; IP provisioning mode = IPv6

Wed May 25 19:45:55 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 19:45:55 2022        Critical (3)           Unicast Maintenance Ranging attempted - No response - Retries exhausted;

Wed May 25 19:45:55 2022        Critical (3)           16 consecutive T3 timeouts while trying to range on upstream channel 2;

Wed May 25 19:46:22 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 19:46:22 2022        Critical (3)           Unicast Maintenance Ranging attempted - No response - Retries exhausted;

Wed May 25 19:46:22 2022        Critical (3)           16 consecutive T3 timeouts while trying to range on upstream channel 1;

Wed May 25 19:46:30 2022        Critical (3)           Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Wed May 25 19:50:50 2022        Critical (3)           Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;

Wed May 25 19:51:04 2022        Notice (6)            Honoring MDD; IP provisioning mode = IPv6

EG

Expert

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94.3K Messages

1分前

O/k so 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) / 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 (Cable Modem Termination System) to check 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 !

Visitor

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2 Messages

@EG​ I can tell you what is likely the culprit as it is with my problem, too.

It has to do with an old drop tap that is meant for the old analog cable standard, you know the 800 MHz bandwidth, other frequencies are attenuated. Heck, if they amplify the signals enough it will pass the drop tap but at what cost in quality of the signal. What other issues does it cause on the near and far ends?

Instead of replacing an old out of date drop tap for everyone connecting to it, they would rather say it's CPE problems, etc. Anything but replacing that [Edited: "Language"] tap, it's amazing what the techs tell me is wrong. I've gone up on a man lift (scissorlift) snapped photos of the old unit, showed when it was manufactured. What is required for the speeds they're trying to push to people out here, which is 2 GHz (2000 MHz), not 800 MHz. Of course they could solve all this [Edited: "Language"] and just run fiber from the vault to the house and put a fiber to copper converter in or have us run straight fiber on our modems.  Would also be smart to get away from GPONs / EPONs, stick with fully packetized networks. Essentially the fiber optic would be Metropolitan Optical Ethernet connection.

(edited)

Visitor

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10 Messages

1分前

How long does it take for comcast to reach out to me about this? 

Official Employee

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590 Messages

Hello, @user_4fdec4! Thank you for reaching out for support, let's further review the modem signals. Please send us a Direct Message with your first and last name. The message icon is located at the top right of the Community Forum page, clicking on the message icon will allow you to initiate a chat conversation with us directly. Please ensure you are sending your message to our 'Xfinity Support' handle. 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
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EG

Expert

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94.3K Messages

1分前

It may have fallen through the cracks.. I'll attempt to re-escalate this.

Visitor

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10 Messages

1分前

Adding some additional information, I’ve had four t4 timeouts today…. 

Visitor

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10 Messages

1分前

Xfinity has now told us three times that the issue is fixed but the timeouts keep happening.  In the direct message they told me even if we get a call that the issue is fixed, we shouldn’t cancel the tech appointment...  Even though the people that call to say they fixed the issue tell us we should cancel the appointment.  There is literally no communication between the different departments at xfinity.  And the fact that we’ve been told the issue has been fixed when it clearly hasn’t is incredibly annoying.  

Visitor

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2 Messages

@user_4fdec4​ If you own your own modem, that's their subtle hint to get one of their. 

But I digress...

I bought and own my own modem as well.

The problem lies in the firmware they are using for your modem. 

It's model and manufacturer specific, it's not 100% compatible with your hardware, lots of T3 and T4 timeouts, as well as the infamous Out of Range error messages. What that means is that the values they're trying to write to your registers in the modem either don't have those values, meaning going that high or low or they don't exist at that specific address they're trying to apply the values to in the first place.

The techs that come out to the house are daft when it comes to that sort of thing, the software developers in Comcast Xfinity are daft because they don't realize that every manufacturer uses different chipsets and passive hardware. There is no 100% compatible and compliant DOCSIS series modem anywhere in the industry, including Cisco / Linksys. Manufacturers of said chipsets and associated manufacturers of modems (sometimes they're the same group) can't agree on what they need to standardize and follow string literal and which they can screw off on (they think as much as they can is the only answer).

Each manufacturer, model and subversion needs a separate firmware update, even from year to year these modems can change, so new firmware file for that version, too.

Comcast Xfinity is trying to avoid creating and uploading 100s of different firmware files with all their different speed grade profiles, this actually makes sense but they don't really even try to be honest about it. 

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