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

I don't think my data collection will be looked at or make a difference to Comcast.  I am collecting the data so that I might learn more about the problem.  If for example, I knew say a time of day when the problem was more likely to happen, that would be a good time to call Comcast in hopes that they would see it.  The problem has been occuring infrequently enough (so far) that it hasn't figure in to when I call them.  If they can't see/document the promblem from their tests, we are left completly on our own. 

I followed your issue (I've been experiencing the same problem). Just posted my own problem with my modem-router's most recent data (only one instance, though): https://forums.xfinity.com/t5/Your-Home-Network/Intermittent-T-3-T-4-and-MDD-Timeouts-Please-fix-our/td-p/3349988.

I live in a very hot area, so your heat theory seems very plausible to me.

I still see how heat could cause such a problem, but in my case I am not seeing the data (so far) to back up my idea.  Maybe they fixed something.  For almost that last 5 days I have had no errors in the logs and the high temps have been from about 85 to 91.  I wonder if they really did fix something.  Only time will tell.

Hey, I've been following this thread as well and having consistent T3 and T4 timeouts. I've exhausted every option Comcast has given me with the issue, including live tech support as well as over the phone. In the end, they told me they had no one they could send out to fix the issue, and so I'm stuck in the same boat as some of you. Has anyone gathered any more information about what can be done?

Here is an idea.  Depending on how friendly you are with your neighbors, ask them if they have Comcast and if they have had any temporary short term outages.  If they aren't tech savy, they may not know or be able to descern between a slow/down website and a cable outage.  If you know them well enough, you could offer to look at their modem logs.  If they are having T3s (and especially if those coincide with yours,) you could get them to call Comcast when you see the problem (as they are most likely seeing a problem at that time also.)  If enough people in an area call at the same time, maybe Comcast will listen and do something.

I don't have neighbors that I am that friendly with, but my idea may work for others.  Good luck.

 I've had this problem in the past back in 2016. I am experiencing the same issue now that I am working from home due to COVID, hence the reason why I got to this thread.  Right now, I am getting the same 3 Log entries below about every 10 miinutes.

 Here is another idea you may want to try with Comcast/Xfinity, which I did in 2016 since I too own the Arris Motorola SB6141 modem.

1.  Purchase a new SB6141 modem locally
   1.  I used the new router to rule out that my modem is bad. It was good. Returned new modem when you know it is not your modem.
2. AND get a new leased modem from Comcast.
   1. To deal with Comcast "We can't help because it is your modem" answer, replace your modem with Comcast's leased modem and have them troubleshoot. This will cost you one month lease charge to your bill.

 Downstream

Upstream

Was Comcast immediately receptive to the problem once you had rented one of their modems and reproted the T3 problems or did you still have to fight with them?

I continue to have issues and I am still tracking them.  I've dropped the temperature data from the graph as I see no correlation at this time.  I still think I will see a reduction in T3/T4 issues come fall and winter, but only time will tell.  Here is a graph of my data so far.

 I am going by memory since it was 4 years ago but not really that they were more responsive . They just had to keep doing the troubleshooting since the modem was theirs. All they could tell me is that everything looked fine. I think I remember changing the switch and the splitters.

 This time, I am planning on replacing the RJ-45 connectors first since the locking tabs are gone. Maybe the wire is comming lose. If that does not helph I'll change the switch.

 I replaced the switch and the connectors that day on 8/2/20. Today, two days later, I do not see any T3 messages in the log page. Everything appears to be working fine. As a matter of fact I see no new messages of any type since 8/2/20. The last log entries are related to me rebotting the modem.

I would like to post our experience with the same problem here.

Since we moved into this house last year, we have been suffering the same T-3 timeout problem. 
To show how crazy the frequency is:

https://imgur.com/3J9IYve

We asked the technician to come in Feb. 2020, and the person checked all the signals and claims things are OK. He claimed that the problem is probably our modem, which had been working perfectly before we move (we also used Comcast's service in that property). We purchased a new modem, still suffered from the problem, that every now and then it spontaneously disconnects and we had to reboot the modem. Most of the times, rebooting works, but there were times things were pretty bad. We complained to Comcast in April, and they asked us to rent their modem. We did, for two months, the problem is still there--when our modem can't connect, Comcast's modem can't neither. 
In between Feb and Aug, I searched numerous discussions on the online forums and got to the conclusion that "it is very hard to find out where the problem might be". The problem is so intermittent and hard to troubleshoot. 

After the fall semester starts, probably due to the high internet traffic here in this small town (online learning), we started to experience much severe intermittent disconnection. It breaks every 10-15 minutes, and kids couldn't even use the internet for the online school.
We complained to Comcast again, and this time, a more experienced person came. 
This person didn't say much but simply went to cut off the old connectors and reinstall the new ones. He did that at the tap, at the boxes outside and inside our house.

Guess what? It has been a month, and we only saw two T-3 timeout error messages. 

We didn't even experience disconnection when those two errors were incurred.

The signal strength of the upstream channels also stabilized significantly. 

I can't believe the solution is this simple. 

My suggestion is to order a tech over and bug him/her to replace all the connectors, if this troubleshooting step has never been performed. 

All the connectors in the house, outside at the box and going up the pole have been replaced.  There is just one piece of cable that hasn't been replaced (the one that goes from the box into the house.)  Maybe I can get them to replace that next time.

I continue to track the problems.  Here is an updated graph.

This isn't conclusive, but as I expected, the data I am collecting shows the number of T3 and T4s has dropped off in the cooler weather. (edited post to get picture to show up)

I wanted to put this in my original thread, but I guess after time you can't reply anymore so I am starting this new one.

Edited to cross out the above line as someone was nice enough to put this back in my main thread.  Thanks!

Here is an update on my T3/T4 tracking. In the last few days, the counts went through the roof. T3s were as follows: Fri 49, Sat 407, Sun 502, Mon 157. The flood stopped on Monday and there has only been one T3 since that time.

A few thoughts:
1. I wonder how/why this got corrected? Did someone call or did Comcast actually see this issue?
2. Will their correction fix the problems I've been seeing for the last few years?
3. Funny that with 1000+ T3s, not once did any of them escalate to a T4 as they often did in the past.

4. Ignoring this exception in the data, the initial data still fits my idea that T3/T4 get worse in the warmer weather months.  Have to keep tracking to find out for sure.