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Upload speed consistently below 1 Mbps. What can I do?

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Frequent Visitor

Upload speed consistently below 1 Mbps. What can I do?

I've been running a speed test (speedtest.net) for the past few weeks. It shows that our upload speed is always less than 1 Mbps. I tried from multiple devices, from multiple jacks around the house and went directly from a laptop to the modem (no wifi router). Also reset the modem several times and had Xfinity reset it remotely several times.

 

An Xfinity technician visited and said that all looks ok outside the house. He ran a speed test in the house on his own device and also saw the upload is less than 1 Mbps but could not find a reason, so he just left and said they can't do anything about it right now.

 

This slow speed is causing lots of timeouts and other connectivity problems. I'm trying to work at home but I might be forced to go to an office 20 miles away.

 

Do you think it might be related to the amplifier in the box outside?  Anything else to try to troubleshoot this?  Obviously, Xfinity is not going to help right now.

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Expert

Re: Upload speed consistently below 1 Mbps. What can I do?

Start here;


https://forums.xfinity.com/t5/Your-Home-Network/Internet-Troubleshooting-Tips/m-p/3310447#M316652



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Frequent Visitor

Re: Upload speed consistently below 1 Mbps. What can I do?

Thanks EG. Here are my modem's stats. But the Xfinity technician used his own device to test our connectivity and speeds (independent of our modem) and agreed that we are barely functional, especially with upload speeds.  Do you see anything abnormal about these stats?  Thanks.

 

Frequency start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency

<tabindex=-1>Startup Procedure</tabindex=-1>
Procedure Status Comment
Acquire Downstream Channel 639000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK d11_m_cm1000_extremepro_c01.cm
Security Enable BPI+
IP Provisioning Mode Honor MDD IPv6 only

<tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked QAM256 29 639000000 Hz 2.6 dBmV 38.5 dB 613326222 97 0
2 Locked QAM256 1 459000000 Hz 2.7 dBmV 39.2 dB 606771532 21 0
3 Locked QAM256 2 465000000 Hz 2.9 dBmV 38.8 dB 606791712 38 0
4 Locked QAM256 3 471000000 Hz 3.0 dBmV 39.0 dB 606774307 58 0
5 Locked QAM256 4 477000000 Hz 3.1 dBmV 38.7 dB 606822311 56 0
6 Locked QAM256 5 483000000 Hz 2.9 dBmV 38.5 dB 638038820 1 0
7 Locked QAM256 6 489000000 Hz 3.1 dBmV 39.0 dB 638051415 28 0
8 Locked QAM256 7 495000000 Hz 2.8 dBmV 38.5 dB 638064017 3 0
9 Locked QAM256 8 507000000 Hz 2.6 dBmV 38.7 dB 638078425 11 0
10 Locked QAM256 9 513000000 Hz 2.5 dBmV 38.8 dB 606908427 46 0
11 Locked QAM256 10 519000000 Hz 2.6 dBmV 38.4 dB 638100186 31 0
12 Locked QAM256 11 525000000 Hz 2.7 dBmV 38.7 dB 638112688 7 0
13 Locked QAM256 12 531000000 Hz 2.6 dBmV 38.9 dB 638125106 27 0
14 Locked QAM256 13 543000000 Hz 2.4 dBmV 38.6 dB 638138577 62 6
15 Locked QAM256 14 549000000 Hz 2.4 dBmV 38.6 dB 638152053 37 0
16 Locked QAM256 15 555000000 Hz 2.6 dBmV 38.7 dB 638164413 13 0
17 Locked QAM256 16 561000000 Hz 2.8 dBmV 38.7 dB 439518174 11 0
18 Locked QAM256 17 567000000 Hz 2.9 dBmV 39.0 dB 439533241 44 0
19 Locked QAM256 18 573000000 Hz 2.7 dBmV 38.8 dB 439549446 35 0
20 Locked QAM256 19 579000000 Hz 2.7 dBmV 38.8 dB 439565337 53 0
21 Locked QAM256 20 585000000 Hz 2.5 dBmV 38.8 dB 439581215 68 3
22 Locked QAM256 21 591000000 Hz 2.7 dBmV 38.7 dB 439597175 56 1
23 Locked QAM256 22 597000000 Hz 2.8 dBmV 38.7 dB 439612764 81 1
24 Locked QAM256 23 603000000 Hz 2.8 dBmV 38.4 dB 439629148 40 0
25 Locked QAM256 24 609000000 Hz 2.8 dBmV 38.6 dB 439644917 53 0
26 Locked QAM256 25 615000000 Hz 2.7 dBmV 38.3 dB 439660294 79 0
27 Locked QAM256 26 621000000 Hz 3.0 dBmV 38.3 dB 439637031 84 0
28 Locked QAM256 27 627000000 Hz 2.8 dBmV 38.7 dB 439653326 99 0
29 Locked QAM256 28 633000000 Hz 2.7 dBmV 38.3 dB 439699107 93 4
30 Locked QAM256 30 645000000 Hz 2.6 dBmV 38.4 dB 439709877 118 0
31 Locked QAM256 31 651000000 Hz 2.7 dBmV 37.9 dB 439732588 81 0
32 Locked QAM256 32 657000000 Hz 2.8 dBmV 38.4 dB 439718718 78 0

<tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power
1 Locked ATDMA 1 17300000 Hz 43.5 dBmV
2 Locked ATDMA 2 23700000 Hz 43.5 dBmV
3 Locked ATDMA 3 30100000 Hz 43.5 dBmV
4 Locked ATDMA 4 36500000 Hz 41.5 dBmV
5 Locked ATDMA 5 41200000 Hz 47.5 dBmV
6 Not Locked Unknown 0 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Hz 0.0 dBmV

<tabindex=-1>Downstream OFDM Channels</tabindex=-1>
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier Number Range Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked 0 159 722000000 Hz 2.4 dBmV 35.8 dB 1126 ~ 2969 386853077 15842235 0
2 Not Locked 0 0 0 Hz 4.2 dBmV 0.0 dB 0 ~ 4095 0 0 0

<tabindex=-1>Upstream OFDMA Channels</tabindex=-1>
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked Unknown 0 0 Hz 0 dBmV
2 Not Locked Unknown 0 0 Hz 0 dBmV

Current System Time: Sat Apr 25 11:07:34 2020
System Up Time: 7:12:06
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Expert

Re: Upload speed consistently below 1 Mbps. What can I do?

Yep. The stats are o/k. We've been seeing a lot of posts here lately about speed issues. I suspect that it may have something to do with capacity / traffic congestion problems due to everyone being home on the internet.



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!
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Frequent Visitor

Re: Upload speed consistently below 1 Mbps. What can I do?

Here's some of our recent speedtest results.  Ping, download and upload.  Note that we're on one of Xfinity's highest speed plans. And a technician visited and didn't fix anything. So, I'm hoping someone on this forum has some answers. One question I have is whether I can test the modem from the cable feed that comes into the box outside our house? Is that technically possible?

 

speedtest.jpg

 

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Frequent Visitor

Re: Upload speed consistently below 1 Mbps. What can I do?

It's not just a speed issue, though. My son had a college exam yesterday and he was required to upload several 20 MB files but they all timed-out, to various websites (office.com, Google Drive, etc.). So we can't even send files that I was able to send through a dial-up modem 15 years ago?

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Frequent Visitor

Re: Upload speed consistently below 1 Mbps. What can I do?

I connected my Netgear CM1000 cable modem directly to the cable feed (outside the house) and the speed test jumped from an average 0.2 Mbps in the house to over 14 Mbps - consistently over several minutes.

 

So, my guess now is that the Commscope splitter/amplier Comcast installed is faulty, another device in our house is causing noise and/or the voltage to the amplier is not consistent.

 

I don't really have the time nor expertise to self-diagnose all of these things -- and I'm paying over $200 per month to Comcast for their "service" -- but after two technicians have been here and left without fixing anything, I really don't have any other choice but to try to fix it myself.

 

Next steps: Pull all cables from the splitter except to the cable modem upstairs and check the voltage to the amplier. I will also probably order a new splitter in case the one we have is causing the problems.

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Frequent Visitor

Re: Upload speed consistently below 1 Mbps. What can I do?

I replaced the splitter that Xfinity provided, made by Commscope, with an Arris amplifier/splitter and this resolved the issue. We're now getting about 15 Mbps upload speeds, up from the usual 0.1.

 

What I don't understand is why, after two technicians visited the house, after about six online chat sessions and several emails and phone calls, not once did an Xfinity rep mention the splitter as a possible reason for the problem. I can't tell you how many modem resets Xfinity did and asked me to do, and the upload speed remained under 1.0 Mbps, but that's all everyone recommended. There has to be an explanation for this.

 

My theory on the bad Commscope splitter is that it started failing due to moisture. An Xfinity technician who visited about eight months ago said he was not able to close the cable box all the way because the splitter was too big, so he zip-tied the box closed, leaving a 1/2-inch gap at the top. I live in the Pacific Northwest, where it rains a lot, and so plenty of rain made its way into the box. The second technician left the box the same way but added weather protection to the cable endpoints. But the Commscope splitter was likely already damaged at that point.