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Intermittent Loss of Service, Modem Log: "No Ranging Response received - T3 time-out"
I continue to have intermittent loss of connectivity about 2 to 5 times a day. The modem will reset on its own and the connection will be re-established. This is really difficult to deal with since conference calls and classes with online exams are now the norm. The modem log shows multiple T3 time outs throught out the day and seems to drop when a T4 - timeout is indicated.
From the modem manufacturer info I noticed the downstream power is a little on the low side plus the upstream power is right on the edge. The manufacture recommends the downstream power to be between -15DbmV and +15DbmV. On the upstream recommendation is above 45Dbmv which is close but usually have 3 or all 4 channels below that. Looking for any help on this. I have been a customer for 25 years but this is really hurting the family. PS: Modem and router are new, dedicated coax cable with no splitter between the outside service connection and the modem. Net effect - same problem.
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Corrected Uncorrectables
1 Locked 256QAM 16 483.00 MHz -10.40 dBmV 37.64 dB 1481 8966
2 Locked 256QAM 8 435.00 MHz -9.50 dBmV 38.98 dB 1230 8560
3 Locked 256QAM 9 441.00 MHz -9.80 dBmV 38.61 dB 1581 9068
4 Locked 256QAM 10 447.00 MHz -9.70 dBmV 38.61 dB 1568 8923
5 Locked 256QAM 11 453.00 MHz -9.50 dBmV 38.98 dB 1568 9813
6 Locked 256QAM 12 459.00 MHz -9.90 dBmV 38.98 dB 1227 7295
7 Locked 256QAM 13 465.00 MHz -10.40 dBmV 38.98 dB 1485 9355
8 Locked 256QAM 14 471.00 MHz -10.20 dBmV 38.61 dB 1555 9403
9 Locked 256QAM 15 477.00 MHz -9.90 dBmV 38.61 dB 1412 9064
10 Locked 256QAM 17 489.00 MHz -10.90 dBmV 37.64 dB 995 7831
11 Locked 256QAM 18 495.00 MHz -10.70 dBmV 37.64 dB 1341 7002
12 Locked 256QAM 19 507.00 MHz -10.60 dBmV 37.64 dB 1308 7522
13 Locked 256QAM 20 513.00 MHz -10.90 dBmV 38.61 dB 1603 10255
14 Locked 256QAM 21 519.00 MHz -10.90 dBmV 38.61 dB 1562 7630
15 Locked 256QAM 22 525.00 MHz -10.90 dBmV 37.64 dB 1286 7702
16 Locked 256QAM 23 531.00 MHz -11.30 dBmV 37.64 dB 2104 7193
17 Locked 256QAM 24 537.00 MHz -11.70 dBmV 36.61 dB 1655 6607
18 Locked 256QAM 25 543.00 MHz -11.80 dBmV 37.36 dB 1320 8406
19 Locked 256QAM 26 549.00 MHz -12.20 dBmV 37.36 dB 1175 9105
20 Locked 256QAM 27 555.00 MHz -11.90 dBmV 37.64 dB 965 6033
21 Locked 256QAM 28 561.00 MHz -11.80 dBmV 37.36 dB 925 5234
22 Locked 256QAM 29 567.00 MHz -11.70 dBmV 37.64 dB 1136 5066
23 Locked 256QAM 30 573.00 MHz -12.10 dBmV 37.36 dB 1222 6108
24 Locked 256QAM 31 579.00 MHz -12.40 dBmV 37.64 dB 1350 7052
25 Locked 256QAM 32 585.00 MHz -11.70 dBmV 37.90 dB 311 3736
26 Locked 256QAM 33 591.00 MHz -11.40 dBmV 37.90 dB 90 3681
27 Locked 256QAM 34 597.00 MHz -11.60 dBmV 38.20 dB 97 3318
28 Locked 256QAM 35 603.00 MHz -12.00 dBmV 37.30 dB 52 2835
29 Locked 256QAM 36 609.00 MHz -12.20 dBmV 37.30 dB 102 2966
30 Locked 256QAM 37 615.00 MHz -12.40 dBmV 37.30 dB 58 1836
31 Locked 256QAM 38 621.00 MHz -11.90 dBmV 37.90 dB 84 2914
32 Locked 256QAM 39 627.00 MHz -11.70 dBmV 37.60 dB 51 2682
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 1 5120 kSym/s 36.50 MHz 46.25 dBmV
2 Locked ATDMA 4 5120 kSym/s 17.30 MHz 43.25 dBmV
3 Locked ATDMA 3 5120 kSym/s 23.70 MHz 43.75 dBmV
4 Locked ATDMA 2 5120 kSym/s 30.10 MHz 44.25 dBmV
Howling_Dog
Frequent Visitor
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7 Messages
5 years ago
The connection from the outside service is a straight run of coax. No spitters or any other device in the line. Ran a dedicated line of RG6 quad shield. Modem is new, Arris SB6190 and is on the list of recommended devices. The Arris modem replaced a Zoom modem I have had for a couple of years but the problem persists with exactly the same symptoms. Any help would be appreciated. Below is the current contents of the modem log which seems to hold about 20 of the lastest events. At least one outage should be captured in this log around 11:50ish.
Time Priority Description
Thu Jul 23 11:49:39 2020 6 TLV-11 - unrecognized OID;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 11:54:09 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 11:58:21 2020 3 Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 12:01:00 2020 6 TLV-11 - unrecognized OID;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 12:01:09 2020 3 Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 13:49:28 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:40:59 2020 3 Ranging Request Retries exhausted;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:40:59 2020 3 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:41:23 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:47:47 2020 3 Ranging Request Retries exhausted;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:47:47 2020 3 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:48:11 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:55:48 2020 6 TLV-11 - unrecognized OID;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 14:56:28 2020 5 RCS Partial Service;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 15:16:18 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 15:23:06 2020 5 RCS Partial Service;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 15:32:46 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 15:33:15 2020 5 RCS Partial Service;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 15:44:22 2020 3 No Ranging Response received - T3 time-out;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
Thu Jul 23 15:44:46 2020 5 RCS Partial Service;CM-MAC=a4:98:13:cb:e3:e1;CMTS-MAC=00:01:5c:74:08:50;CM-QOS=1.1;CM-VER=3.0;
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EG
Expert
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110.3K Messages
5 years ago
The downstream power is low to being out of spec on some channels and it may be intermittently fluctuating even lower to out of spec levels on the rest. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test
If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.
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Steve_in_co
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1 Message
5 years ago
Checking the Internet Troubleshooting tips here is the signal level specs listed:
Downstream power level: min -10dBmV, max +10dBmV
Downstream signal to noise: Min 35dB
Upstream Power Level: min +35dBmV, Max +50dBmv
Upstream signal to noise: 31dB
An update on my end. Here is the latest stats from the modem log.
Ok downstream power is within range so is signal to noise. Upstream power is within range but upstream signal to noise is not displayed.
Note that downstream power has increased since the last post. What has changed is the installation of a new pull of RG6 Quad Sheild Coax from termination of the underground service on the side of the house to the modem. Direct connection with no splitters and just connectors on each end. Still see T3 time outs in the log. Just connected new pull last night so will see what happens. The short outages are intermittent so I'm not holding my breath on this but the new cable pull did improve the downstream power levels.
Current System Time: Fri Jul 24 09:54:11 2020
Time Priority Description
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EG
Expert
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110.3K Messages
5 years ago
Well the downstream power is still on the weak side. 0 to +5 dB is the preferred area.
The upstream SNR can only be read by them from their end. When in doubt, get a tech out as stated. Good luck !
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Howling_Dog
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7 Messages
5 years ago
Ok I thought I was doing better with the replacement of the original house coax, vintage 1989, with a new pull of dedicated RG6 quad shield with no splitters, cable clamps, or other devices attached. Downstream power looks better and SNR looks better too. But just as I thought I might be over the intermittent loss of service issue it shows up again. Very frustrating. Looks to me like everytime a T4 time out error is registered the modem goes offline and has to re-intialize. Service is restored after the approximatly 5 minuite process. This seems to happen most frequently between 11:30am and about 6PM. Now everthing has been replaced, router, modem, coax to the service hookup point on the outside of the house. What a time consuming, expensive, and frustrating experience this continues to be. Given working from home and online school connectivity is critical.
How can I connect with some techinical support from Comcast other than the usual lets reset the modem script that the front line service folks? Who can I call and what is the contact information for some technical help that can really help? Can someone check at the head end of the system and look at the what might be the issue here?
Time Priority Description
Current System Time: Sun Jul 26 19:31:45 2020
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avannik
New Poster
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1 Message
5 years ago
Same issue here. The modem log is full of "No Ranging Response received - T3 time-out;" until the connection is finally lost. Mine does not reboot on its own, need to do that myself. It was fine a week or two after we got connected to Xfinity, but now outages become more and more frequent and interfere with my work. RF parameters look OK. Research on the internet tells me the issue is cable-related and can only be resolved by the specialists. However, no means of contact is provided for such case by Xfinity. Am I to speak with their chatbot for that? Must I visit an Xfinity store? They are of absolutely no help.
If I am mistaken and the human tech support do have an email or phone which opens into the outer world, please let me know.
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Howling_Dog
Frequent Visitor
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7 Messages
5 years ago
I had a zoom modem which did not "reset" itself and come back online. In my effort to solve the issue I replaced it with a Arris SB6190. At least it will figure out the connection is lost and re-establish the connection. This is important since the wife is not real happy about unplugging the modem and getting a connection back.
BTW: A co-worker has the same Comcast issue along with his mothers' Comcast connection. He is in the general area but not on the same Comcast network segment. Also there are some great youtube videos about T3 and T4 time outs.
One thing I wonder about is my downstream power is in the -7dbmv range which is acceptable by Comcast standards (+10dbmv thru -10dbmv) but wonder if it would help if the downstream power level was more like 0dbmv to +2dbmv range? Is the power level a function of the modem to Comcast communications negotiations? Is it only of function of the infastructure cable connections? Can this be adjusted by Comcast?
Also the intermittent loss of communications happens primarily in the time frame of 11:30am to about 6pm. This is very suspicious. Could this be a high traffic time on the section of the Comcast network that I am connected to? Is this a symptom of Comcast inability to deal with more traffic due to the current home bound situation? All I want is a stable internet connection which is what I pay for. Really don't want to change providers but this is getting really old.
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Howling_Dog
Frequent Visitor
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7 Messages
5 years ago
Good information about cable modems and broadband infastructure from Volpe Firm. See youtube videos from this guy. Learning more than I ever wanted to know about this in an effort to just get stable internet service. Can anybody help from Comcast here?
https://volpefirm.com/
I seem to get a drop in service when I get a T4 timeout in the modem log. The modem re-registers and service will be restored in about 5 min. I seem to always get T3 time outs but is able to maintain an internet connection when just T3's happens.
From Volpe:
T4 Timeout ( Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received )
Explanation: The cable modem did not received 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. This error message is DOCSIS event message is R04.0, Ranging Request.
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Howling_Dog
Frequent Visitor
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7 Messages
5 years ago
Put in my last ditch effort to at least minimize this problem. I moved the modem to the basement so I could have a 6 foot section of RG6 from the outside of the house to the modem. Than ran the ethernet to the router from there. So the downstream power is in a better place but within 10 min of doing this another intermittent outage. I've done all I can do on this one.
Anybody from Comcast there?????? A phone number for technical support other than someone to tell be to reset the modem???? Could use some support on this!
Current System Time: Tue Jul 28 19:08:06 2020
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Kupua
Visitor
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1 Message
4 years ago
I know this is a year old, but wanted to say that I suffer the exact same issues, for years now. Like you I went through all of the hoops replacing stuff. Comcast is of no help and gives generic responses, or tells me it is my responsibility.
My Downstream and SNR is good. But the problems persist. This has to be a service interrupt...
I just wanted to show that even with really good numbers, the issue persists.
(edited)
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