Community Forum

Slow upload speed. Only one upstream channel locked.

Highlighted
Frequent Visitor

Slow upload speed. Only one upstream channel locked.

Upgraded to Gigabit package to get faster upload speed (35Mbps),  but I'm still maxing out at 10Mbps.  I noticed on my cable modem I only have one upstream channel locked:

 

Upstream Bonded Channels (Partial Service)
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 77 5120 Ksym/sec 36500000 Hz 44.5 dBmV
2 Not Locked Unknown 78 0 Ksym/sec 30100000 Hz 0.0 dBmV
3 Not Locked Unknown 79 0 Ksym/sec 23700000 Hz 0.0 dBmV
4 Not Locked Unknown 80 0 Ksym/sec 17300000 Hz 0.0 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
 

 

I even tried connecting the cable modem directly to the line coming into the house and got the same result.  Plus, it takes about 20 minutes for the cable modem to finish starting up.   Presumably while it tries to lock those channels?

 

Here's a sample of the eventlog on the modem, it is full of these errors:

Time Priority Description
Tue Apr 21 14:52:52 2020 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=28:80:88:00:cd:a0;CMTS-MAC=00:01:5c:86:7c:59;CM-QOS=1.1;CM-VER=3.1;
Tue Apr 21 14:49:52 2020 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=28:80:88:00:cd:a0;CMTS-MAC=00:01:5c:86:7c:59;CM-QOS=1.1;CM-VER=3.1;
Tue Apr 21 14:49:52 2020 Critical (3) Ranging Request Retries exhausted;CM-MAC=28:80:88:00:cd:a0;CMTS-MAC=00:01:5c:86:7c:59;CM-QOS=1.1;CM-VER=3.1;

 

 

 

Here's the downstream channels, I think they look ok:

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 13 519000000 Hz 0 dBmV 44.2 dB 0 0
2 Locked QAM256 10 501000000 Hz -0.3 dBmV 44 dB 0 0
3 Locked QAM256 11 507000000 Hz -0.1 dBmV 44 dB 0 0
4 Locked QAM256 12 513000000 Hz -0.1 dBmV 44 dB 0 0
5 Locked QAM256 14 525000000 Hz 0 dBmV 44.2 dB 0 0
6 Locked QAM256 15 531000000 Hz 0.1 dBmV 44.2 dB 0 0
7 Locked QAM256 16 537000000 Hz 0.2 dBmV 44.3 dB 0 0
8 Locked QAM256 17 543000000 Hz 0.2 dBmV 44.2 dB 0 0
9 Locked QAM256 18 555000000 Hz 0 dBmV 44.2 dB 0 0
10 Locked QAM256 19 561000000 Hz 0 dBmV 44.1 dB 0 0
11 Locked QAM256 20 567000000 Hz 0 dBmV 44.2 dB 0 0
12 Locked QAM256 21 573000000 Hz 0.1 dBmV 44.1 dB 0 0
13 Locked QAM256 22 579000000 Hz 0.1 dBmV 44.2 dB 0 0
14 Locked QAM256 23 585000000 Hz 0.1 dBmV 44.2 dB 0 0
15 Locked QAM256 24 591000000 Hz -0.1 dBmV 44.1 dB 0 0
16 Locked QAM256 25 597000000 Hz -0.2 dBmV 44 dB 0 0
17 Locked QAM256 26 603000000 Hz -0.1 dBmV 44 dB 0 0
18 Locked QAM256 27 609000000 Hz -0.2 dBmV 44 dB 0 0
19 Locked QAM256 28 615000000 Hz -0.1 dBmV 44 dB 0 0
20 Locked QAM256 29 621000000 Hz -0.3 dBmV 43.8 dB 0 0
21 Locked QAM256 30 627000000 Hz -0.5 dBmV 43.6 dB 0 0
22 Locked QAM256 31 633000000 Hz -0.5 dBmV 43.6 dB 0 0
23 Locked QAM256 32 639000000 Hz -0.5 dBmV 43.6 dB 0 0
24 Locked QAM256 34 645000000 Hz -0.6 dBmV 43.6 dB 0 0
25 Locked QAM256 35 651000000 Hz -0.8 dBmV 43.5 dB 0 0
26 Locked QAM256 36 657000000 Hz -1 dBmV 43.3 dB 0 0
27 Locked QAM256 37 663000000 Hz -1 dBmV 43.3 dB 0 0
28 Locked QAM256 38 669000000 Hz -1.1 dBmV 43.2 dB 0 0
29 Locked QAM256 39 675000000 Hz -1.2 dBmV 42.2 dB 0 0
30 Locked QAM256 40 681000000 Hz -1.4 dBmV 43.1 dB 0 0
31 Locked QAM256 41 687000000 Hz -1.5 dBmV 42.9 dB 0 0
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
 
Highlighted
Frequent Visitor

Re: Slow upload speed. Only one upstream channel locked.

Just wanted to add the OFDM channel info:

Downstream OFDM Channels
Channel Lock
Status
Modulation /
Profile ID
Channel
ID
Frequency Power SNR /
MER
Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 33 693000000 Hz -1.2 dBmV 42.1 dB 1108 ~ 2987 40150883 21265435 0
2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV
Highlighted
Expert

Re: Slow upload speed. Only one upstream channel locked.

First, try power-cycling the modem several times to see if it will lock on to more upstream channels.



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Frequent Visitor

Re: Slow upload speed. Only one upstream channel locked.

Still no luck.   Only one locked channel.

 

Same results when connected directly to the incoming line.  Normally hooked up with just one splitter.

 

And it takes forever to come online... and the uplink light never stops blinking, even when it is online.

Highlighted
Expert

Re: Slow upload speed. Only one upstream channel locked.

They may have put a high pass filter on your line that only a tech can remove from the tap. The next thing to do is to schedule a tech to come out and investigate. Good luck !!



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Frequent Visitor

Re: Slow upload speed. Only one upstream channel locked.

Why would they do that?

And why wouldn't they tell me if they did?

 

Really don't want to have a tech or anyone have to come in my house, given the current circumstances with the pandemic and all.

Highlighted
Expert

Re: Slow upload speed. Only one upstream channel locked.

No clue..... I'm not an employee.... The filter would be outside of your home, likely to be on the tap on the pole / pedestal.



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!