How to get Comcast to help me with "No Ranging Response received - T3 time-out" ?

3-Critical R2.0 No Ranging Response received - T3 timeout:

Explanation. The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also lower the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem's power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process.
Recommended Action No action is needed if this is an occasional problem. Check the upstream transmit power for the cable modem to see if it is at or near the maximum allowable levels. Check the RF plant for cabling or connector issues that could generate sufficient noise to lose MAC-layer management messages.

3-Critical H501.8 HFC: T4 Timer Expired:

Explanation. The cable modem did not receive a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds). The cable modem is resetting its cable interface and restarting the registration process. Typically, this indicates an occasional, temporary loss of service, but if the problem persists, check for possible service outages or maintenance activity on this particular headend system.
Recommended Action for your Provider: Check the configuration on the CMTS. Check the cable plant for RF connector or cabling issues that could be generating noise on the downstream.

Just minutes after my last post the modem went down.  Here is the log.

Modem Reset Log 

What is the most effective way for me to report this to Comcast so they will help?  Do I report it as a T3 problem or a T4 problem or both? Is it best to play dumb  or do I share what I know about the problem?

I need to plan my stratagy.  Although there have been no issues since June 4, I bet they will start up again the next really hot day we have here.

The problem is happening more often.  I wish the service would completely die so I could get someone from Comcast to help!

The log files are filling up now due to the larger number of errors.  I wrote a script to collect the log files.  As long as I keep the computer up and running I'll be able to have a basically unlimited  history of log entriesnow .  I also realized that the first signal of trouble is not being able to ping the modem.  I am recording that along with what comes from the modem logs.

The script is paying off.  I can see how much more the problem is happening now.  At one time (Monday afternoon,) the modem rebooted but never reconnected.  The "online" light was off (meaning no connection.)  Called Comcast, they tried to reboot the modem, it obviously failed.  They set up an appointment for me on Wednesday. About an hour later they texted me saying they had fixed a problem in my area.  I rebooted the modem and everything worked.  They also asked if I wanted to cancel my appointment.  I cancelled it because I didn't want to be charged if they came out and there was no problem.

I don't know if the problem is fixed or not.  I'll have to keep monitoring the logs.  In the last 12 hours there have been four T3 timeouts, no other errors, no reboots and only one ping failure. My script is doing pings to the modem and log monitoring/collection every minute. 

I'll keep posting until this gets resolved in hopes someone else can benefit from all this.  I am currently not too optimistic that things have been fixed.  I would love to be wrong about that.

The problem persists.  On Wednesday I called Comcast and actually got an appointment for them to call me on Saturday.  Based on that call they *might* set up an appointment for someone to come out and look at things.

Later in the day (Wednesday) the errors were happening less often.  Thursday and Friday (so far) there were only four t3 errors, no modem reboots and nothing else in the logs.  Without an explanation why there are now fewer errors, I can't believe that this issues is fixed.  After 3 years off and on, it certainly didn't fix itself. 

For what it is worth, a cool front came in Wednesday afternoon and it has been cooler since then.  That goes along with my theory about this problem possibly being heat related.

FWIW, higher ambient temperatures creates more resistance in the lines which amounts to higher upstream power levels and lower downstream power levels. There are AGC (Automatic Gain Controls) In their line amplifiers on the poles but sometimes these are purposefully disabled by their line / maintenance techs for their own reasons or they are malfunctioning.

Comcast tech. did not call Saturday evening as the last person I talked to said they would.  Instead I got an automated call setting up an appointment for Sunday evening. 

Tech came out Sunday and couldn't find a problem.  I told him it was intermittent.  He said he would write it up as a "line call, non customer impacting" since he had no evidence of a problem.    He gave me his supervisor's number. I called and left a message with my number asking to be contacted if I could provide any more information to help in any way.

There have been no issues in the log file at all for the last 48 hours at the time I am posting this.  Once again I am predicting the problem will come back with hot weather.  If the forecast holds up, that will be near the end of this week.

As was forcast, the temperature got hotter around here.  Although I did see more errors as the temperature rose, I saw far fewer than before.  In the last week I've seen about nine T3 errors, two T4 errors and one modem reboot.  The majority of those happened on Friday and Saturday.  The reboot happened Saturday and no errors have been logged (so far) today, Sunday.

Maybe there are mutlitple problems along the line and they fixed the biggest one.   I hate intermittant problems.

I'll still keep monitoring the modem and reporting back here.

Well, well.  Woke up this morning to see and additional ten T3s,  four T4s, and 2 reboots.  So much for the problem being solved.

It is starting to appear that the heat issue might be a cumulitive one.

Here is how I started tracking my T3/T4 issues for the last 18 days.  I've put the high temperature for the day on the graph to see if there is any correlation between higher temperatures and issues.  Either way, just the T3 and T4 data by itself may be usefull to have.

Following your thread. I have an Arris Surfboard SB6190, live in Michigan. Everything was fine over the winter, but I've been getting increasingly frequent T3 and T4 timeouts as the temperature has increased. Connection drops on average 3 times a day now for 5-30 minutes.

Replaced RG59 coax with RG6 and removed splitter and the problem persists, although my downstream power levels went from 2 dBmV to 11 dBmV.

Downstream channels 256QAM; power level 11.2 +/- 0.3 dBmV; SNR 38.9 +/- 0.3 dB

Upstream channels ATDMA; power level 36.5 +/- 0.5 dBmV

Afraid to start the process of engaging Comcast and having the burden of diagnosis left completely to me, like it has been for rwkeating.

1) I was considering creating a script like keating has done. Is historical data like this useful to Comcast support/techs, or will it be ignored?

2) Is there equipment I could invest in to troubleshoot connectivity myself? I'm a network admin by profession but all Cisco LAN technologies, no ISP experience. It's very frequent that friends, family, or myself have intermittent issues with cable internet.