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Constant speed spikes between 0 Mbps and 120 Mbps

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Frequent Visitor

Constant speed spikes between 0 Mbps and 120 Mbps

So I have tried talking to Comcast CS 12 times now, and had 3 seperate techs out to house in the past 3 months. For a bit of history I have been in IT for 10 years, I have never had an issue with comcast in the past 3 years Ive had them, until the beginning of this year.

It all started with some random down spiking around midnight my time, I thought it was odd cause it wasn't prime time, and my computer (Ethernet) was the only device active on the network. I didn' think much of it until it started happening the next night, and every night after. So that's when I started to call CS. The said that it was probably the modem, having packet lose issues. Good thing was, I already had a new modem on the way. Setup the new one that week and boom, fixed it for about 3 days, then back at it again. A few more days pass and now the dropping is happening throughout the whole day, and instead of spiking down every 5 or so minutes, not its about every 20 seconds. I had a tech come out and check the house (no splitter, and nothing else is connected with the modem other than my computer.) Line outside "looked fine" so he dug into it and turned out the area was having issues, so he setup an appointment for the local box to be looked at. I hear back about 3 days later saying its fixed, and boom! Again fixed, but only for a week this time... Finally I have another person come out that says it was the local box again, but then instead he just sent out another person to the home the next day. That technician found that my lead into the house was about 20 feet longer than it needed to be and the extra cable had been coiled up and dug under the lead into the home. He snipped both ends and reconnected the cable to shorten it, and boom, fixed again. For 2 weeks... And now I am back at it again, it has now been about 3 weeks of me pushing through this hoping that something will change on comcast end, but clearly it isn't, so I figured Id come here to get some ideas. Everytime I have talked to support over the phone they keep saying that they are getting packet lose on their end, my only last thought is that somewhere on the cable in the ground it is cut or something and it is giving this interference. I can try to provide as much info as I can as needed, but any ideas or help is much appreciated.

Frequent Visitor

Re: Constant speed spikes between 0 Mbps and 120 Mbps

Seems like my net lagged while I posted this, and it sent it twice, Im sorry for that, but since this one already has a view, this should be the main thread.

Frequent Visitor

Re: Constant speed spikes between 0 Mbps and 120 Mbps

UPDATE: I have been trying to connect and login to the modem to get some logs but I can't even see it when I put in 10.0.0.1, which is the IP Ive always used to bring it up, just shows page unavailable.

Expert

Re: Constant speed spikes between 0 Mbps and 120 Mbps

I'm going to try escalating your ongoing issue to the Comcast corporate employees that are available to these boards. You should get a reply here in your topic.


I am not a Comcast Employee.
I am a fellow customer, 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.

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Frequent Visitor

Re: Constant speed spikes between 0 Mbps and 120 Mbps

Cable Modem

HW Version:1.0
Vendor:Cisco
BOOT Version:3.4.22.4
Core Version:3.12.14
Model:DPC3941T
Product Type:XB3
Flash Part:128 MB
Download Version:2.3.10.13_5.5.0.5
Serial Number:289590692
Downstream
Channel Bonding Value
Index
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Lock Status
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Frequency
609 MHz
483 MHz
489 MHz
495 MHz
501 MHz
507 MHz
513 MHz
519 MHz
525 MHz
531 MHz
537 MHz
543 MHz
573 MHz
579 MHz
585 MHz
591 MHz
597 MHz
615 MHz
627 MHz
633 MHz
651 MHz
657 MHz
663 MHz
669 MHz
SNR
40.946 dB
40.946 dB
40.366 dB
40.946 dB
40.366 dB
40.946 dB
40.946 dB
40.946 dB
40.366 dB
40.366 dB
40.946 dB
40.946 dB
40.946 dB
40.946 dB
40.366 dB
40.946 dB
40.946 dB
40.946 dB
40.366 dB
40.946 dB
40.366 dB
40.366 dB
40.946 dB
40.366 dB
Power Level
11.500 dBmV
11.300 dBmV
11.300 dBmV
11.100 dBmV
11.100 dBmV
11.100 dBmV
11.100 dBmV
11.200 dBmV
11.600 dBmV
11.800 dBmV
11.700 dBmV
11.600 dBmV
11.600 dBmV
11.600 dBmV
11.600 dBmV
11.500 dBmV
11.400 dBmV
11.200 dBmV
11.000 dBmV
10.900 dBmV
10.900 dBmV
10.700 dBmV
10.600 dBmV
10.700 dBmV
Modulation
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
Upstream
Channel Bonding Value
Index
1
2
3
Lock Status
Locked
Locked
Locked
Frequency
29 MHz
35 MHz
23 MHz
Symbol Rate
5120 KSym/sec
5120 KSym/sec
5120 KSym/sec
Power Level
40.500 dBmV
40.500 dBmV
39.750 dBmV
Modulation
64 QAM
64 QAM
64 QAM
Channel Type
ATDMA
ATDMA
ATDMA
Expert

Re: Constant speed spikes between 0 Mbps and 120 Mbps

Not certain that it is the root cause of the problem but the downstream power is high. For giggles, you could try using a 6 dB attenuator pad in the coax line to the modem;

 

https://www.amazon.com/6db-Attenuator-Pad-1-each/dp/B0013L48XA



I am not a Comcast Employee.
I am a fellow customer, 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!
Official Employee

Re: Constant speed spikes between 0 Mbps and 120 Mbps

Hi Zarthro, 

 

I can take a deeper look at your service issues. Can you please confirm your first and last name and the phone number or account number associated with your services in a private message? 

 

To send a private message click on my name "ComcastChe", then click private message me.

I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: Product, Support, Leadership. 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!