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Download speed inconsistent, upload speed barely moving.

Frequent Visitor

Download speed inconsistent, upload speed barely moving.

Ever since 3 days ago I've noticed a decrease in performance in my gigabit internet connection. So I started doing some speed tests with my wired PC. In mid afternoon it seems to be fine but when it starts getting night time things go south. I have a Motorola MB8600 DOCSIS 3.1 approved modem with a netgear nighthawk router. I checked the modem stats and nothing appears to be out of the ordinary from what little I know about cable signals.

 

Speed test: http://speedtest.xfinity.com/results/JQK8L28EB1YTW31

 

Event log: 

Time   Priority   Description 
 Wed Jan 2 12:17:08 2019    Critical (3)   SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:18:24 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:18:24 2019    Critical (3)   Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:18:24 2019    Critical (3)   16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:18:45 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:18:45 2019    Critical (3)   Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:18:45 2019    Critical (3)   16 consecutive T3 timeouts while trying to range on upstream channel 0;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:19:30 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:19:30 2019    Critical (3)   Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:19:30 2019    Critical (3)   16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:19:51 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:19:51 2019    Critical (3)   Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Wed Jan 2 12:19:51 2019    Critical (3)   16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 00:27:54 2019    Critical (3)   REG RSP not received;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 00:55:49 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 01:03:16 2019    Critical (3)   Resetting the cable modem due to docsDevResetNow" 
 Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 01:04:41 2019    Critical (3)   REG RSP not received;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 01:11:38 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 01:14:28 2019    Critical (3)   Resetting the cable modem due to docsDevResetNow" 
 Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 01:15:48 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Time Not Established   Notice (6)   Honoring MDD; IP provisioning mode = IPv6" 
 Sat Jan 5 20:44:06 2019    Notice (6)   TLV-11 - unrecognized OID;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 
 Sat Jan 5 20:55:45 2019    Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:70;CMTS-MAC=00:01:5c:b1:48:49;CM-QOS=1.1;CM-VER=3.1;" 

And here's the stats as of this post.

 

Downstream Bonded Channels    
  
   Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (d Corrected Uncorrected
1 Locked QAM256 14 543.0 5.7 40.7 0 0
2 Locked QAM256 1 459.0 5.7 41.1 0 0
3 Locked QAM256 2 465.0 5.8 41.1 0 0
4 Locked QAM256 3 471.0 6.0 41.2 0 0
5 Locked QAM256 4 477.0 6.1 41.2 0 0
6 Locked QAM256 5 483.0 6.0 41.2 0 0
7 Locked QAM256 6 489.0 5.7 41.2 0 0
8 Locked QAM256 7 495.0 5.4 40.9 0 0
9 Locked QAM256 8 507.0 5.3 40.7 0 0
10 Locked QAM256 9 513.0 5.4 40.9 0 0
11 Locked QAM256 10 519.0 5.4 40.7 0 0
12 Locked QAM256 11 525.0 5.6 41.0 0 0
13 Locked QAM256 12 531.0 5.6 40.8 0 0
14 Locked QAM256 13 537.0 5.8 40.7 0 0
15 Locked QAM256 15 555.0 5.8 40.5 0 0
16 Locked QAM256 17 567.0 6.4 40.7 0 0
17 Locked QAM256 18 573.0 6.6 40.8 0 0
18 Locked QAM256 19 579.0 6.8 40.7 0 0
19 Locked QAM256 20 585.0 6.9 40.8 0 0
20 Locked QAM256 21 591.0 7.0 40.7 0 0
21 Locked QAM256 22 597.0 7.2 40.7 0 0
22 Locked QAM256 23 603.0 7.3 40.7 0 0
23 Locked QAM256 24 609.0 7.3 40.9 0 0
24 Locked QAM256 25 615.0 7.4 40.8 0 0
25 Locked QAM256 26 621.0 7.5 40.8 0 0
26 Locked QAM256 27 627.0 7.5 41.0 0 0
27 Locked QAM256 28 633.0 7.4 40.7 0 0
28 Locked QAM256 29 639.0 7.3 40.8 0 0
29 Locked QAM256 30 645.0 7.5 40.7 0 0
30 Locked QAM256 31 651.0 7.6 40.9 0 0
31 Locked QAM256 32 657.0 7.8 41.0 0 0
32 Locked OFDM PLC 33 690.0 7.7 39.5 0 0



   Upstream Bonded Channels    

  
   Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked SC-QAM 1 5120 35.8 42.8
2 Locked SC-QAM 2 5120 29.4 42.8
3 Locked SC-QAM 3 5120 23.0 43.0
4 Locked SC-QAM 4 5120 16.6 43.0

 

Silver Problem Solver

Re: Download speed inconsistent, upload speed barely moving.

https://forums.xfinity.com/t5/Your-Home-Network/Troubleshooting-Gigabit-internet-speeds/m-p/3145413#...

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Expert

Re: Download speed inconsistent, upload speed barely moving.

For a test, does a computer hardwired directly to the MB8600 modem (no router or WiFi in the mix) have the same problem ?



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Frequent Visitor

Re: Download speed inconsistent, upload speed barely moving.

The results are from the modem being hardwired to my PC. The upload speed stopped slowing down for a couple of days and as of now it just started back.

 

http://speedtest.xfinity.com/results/JQOP8RNXMECT34R

Frequent Visitor

Re: Download speed inconsistent, upload speed barely moving.

Okay this is getting annoying. It happens at completely random times and it's starting to really hurt even my browsing experience.

 

As of 4:30am Eastern:

Speed Results

DOWNLOAD SPEED
153.2 Mbps
UPLOAD SPEED
0.6 Mbps
 
Latency
10 ms
 
Protocol
IPv4
 
Host
Woodstock, GA
Frequent Visitor

Re: Download speed inconsistent, upload speed barely moving.

Also the download speed roller coasters back and forth as shown in this GIF I made.

https://i.imgur.com/SmmBtFn.gifv

Expert

Re: Download speed inconsistent, upload speed barely moving.

The signal stats are o/k but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) / return path 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 to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !



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Frequent Visitor

Re: Download speed inconsistent, upload speed barely moving.

Update: I had a tech come out today. He replaced some connectors and added a splitter. When he was here he said it was all in the green, but shortly after he left it started again. I believe it has to be something beyond the drop to my house at this point.

 

http://speedtest.xfinity.com/results/JQV35A0F1BG9BWI

Official Employee

Re: Download speed inconsistent, upload speed barely moving.

Hi, chasegrn. Thank you for reaching out about this and for providing an update on your situation. If there is something on our end that is contributing to a service issue and it's beyond your home - the service technicians are often able to identify that potential source of the issue and will handle it accordingly by opening a special request order, depending on the situation and on their evaluation. Those are opened as needed and when the technician can tell after running through various diagnostic checks that the issue is sourced from other contributing factors that we have in our control, beyond your premise. Since that wasn't done, I'd like to take a look at the node that supplies service to your location to help determine where we go from here.

 

Please send me a private message with your name and we will go from there.

 

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

Thank you.


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Frequent Visitor

Re: Download speed inconsistent, upload speed barely moving.

Hi Morgan. The technician did tell me he was unable to check signal logs or anything plant related due to an issue with the connectivity of his company phone.

 

As of this morning it seems to have corrected itself again. I hope it will stay this way. I will give it a day or two to see if it stays stable. I will message you if it starts up again.

Official Employee

Re: Download speed inconsistent, upload speed barely moving.

Oh OK, sure. I would still be happy to check it for you in the interim if you'd like, otherwise reaching back out if the concern comes back works too. It's completely up to you. I will be here if you need me. 


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Official Employee

Re: Download speed inconsistent, upload speed barely moving.

It seems like everything is still working for you, chasegrn. Have a good one and take care!


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