U

Sunday, August 11th, 2024 1:55 AM

Spotty connection + very high correctable error rate on main channel

Background

I recently moved into my house maybe 3 weeks ago. My internet speeds are fine whenever I test, but a few times now the internet becomes unreachable even after eg restarting modem. It then self recovers, I haven't noticed exactly how long because I usually switch over to my mobile hotspot as I am working. This affects all devices in the house. Frequently (on and off throughout day), web resources seemingly load very slowly at times despite the speed, everything feels a little sluggish.

I have a google nest wifi router and my xfinity gateway in bridge mode, signal shows as strong (wifi strength, internet speed from end device/router/modem/xfinity app). I haven't directly tested via ethernet to my gateway during a connection interruption, but I don't really see any reason to think there are wifi issues. I'll note that I had the same issue when just using wifi from the gateway directly, it's why I unpacked my mesh network devices as I was concerned about the not-awesome wifi signal.

My questions

  • Any general interpretations of my readings / network behavior (see below for more details)
  • Is it worth scheduling a tech visit? (If so, is there a way to do this that doesn't involve looping through the chatbot troubleshooting over and over...)
  • Any additional troubleshooting worth doing on my own first?

I appreciate the help!

Troubleshooting done

I referred to the connection troubleshooting guide and did the following:

  • reviewed gateway data, everything seems fine except for very high correctable error count on primary channel, more info below
  • fully power cycled gateway, router, etc
  • inspected coax cable inside house
    • it has compression connectors and the pins look fine, no signs of cable wear or kinks
    • ensured the cable is securely fastened to my gateway + ingress point in my house
    • I am using the existing xfinity-provided cable that came with the house, of unknown age... maybe about a year and a half?
    • it does have some excess length, maybe 8 feet all told so it loops around
  • inspected outside cables for any signs of wear
    • The cable goes straight from the carrier box into my house in
    • The exterior coax cable is on the longer end and wraps around the corner of the (small) house, maybe 120 feet total
  • ran public internet speedtests, wifi connectivity tests, mesh tests, xfinity app tests, etc all fine
  • ran ping tests against www.comcast.net, consistently ~80ms with no drops or timeouts
  • ran ping tests against my gateway (10.0.0.1), ~4-10ms without drops
  • checked dhcp lease times... though not sure what i'm looking for. it's on a 24 hour cycle and last was obtained ~ 2 hours ago

Gateway data

Looking in the gateway admin, I see literally no errors in the event logs, just stuff from when the network was set up. All of the power, snr, etc, levels look appropriate in terms of range and relation to one another.

The only thing that stands out is that I have very high correctable error rates on my primary channel (~40-60%). I've rebooted my modem and immediately see uncorrectable errors start to shoot up at the same ratio. See below for the current levels, a snapshot of error rates that spans ~ 5 days, and the current one (which spans ~30minutes).

Model: CGM4140COM

Levels:

Downstream
Channel Bonding Value
Channel ID
44
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
193
194
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
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Frequency
645 MHz
459 MHz
465 MHz
471 MHz
477 MHz
483 MHz
489 MHz
495 MHz
501 MHz
507 MHz
513 MHz
519 MHz
525 MHz
531 MHz
537 MHz
543 MHz
549 MHz
555 MHz
561 MHz
567 MHz
573 MHz
579 MHz
585 MHz
591 MHz
597 MHz
603 MHz
609 MHz
615 MHz
621 MHz
627 MHz
633 MHz
639 MHz
722000000
957000000
SNR
41.4 dB
43.6 dB
43.7 dB
43.8 dB
42.6 dB
41.7 dB
41.8 dB
42.0 dB
42.0 dB
42.2 dB
42.2 dB
42.1 dB
42.3 dB
42.4 dB
42.1 dB
42.2 dB
41.9 dB
42.0 dB
42.1 dB
42.1 dB
41.9 dB
42.0 dB
42.0 dB
41.9 dB
41.9 dB
41.9 dB
42.0 dB
42.0 dB
42.0 dB
42.0 dB
41.7 dB
41.7 dB
42.0 dB
41.9 dB
Power Level
2.2 dBmV
2.0 dBmV
2.1 dBmV
2.1 dBmV
2.1 dBmV
2.1 dBmV
2.1 dBmV
2.1 dBmV
2.1 dBmV
2.1 dBmV
2.0 dBmV
1.9 dBmV
1.8 dBmV
1.7 dBmV
1.6 dBmV
1.6 dBmV
1.4 dBmV
1.4 dBmV
1.5 dBmV
1.4 dBmV
1.4 dBmV
1.6 dBmV
1.7 dBmV
1.7 dBmV
1.8 dBmV
2.0 dBmV
2.0 dBmV
2.1 dBmV
2.3 dBmV
2.3 dBmV
2.2 dBmV
2.2 dBmV
3.8 dBmV
5.2 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
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
OFDM
OFDM
*Channel ID 44 is the Primary channel
Upstream
Channel Bonding Value
Channel ID
1
2
3
4
41
Lock Status
Locked
Locked
Locked
Locked
Locked
Frequency
16 MHz
22 MHz
29 MHz
35 MHz
36 MHz
Symbol Rate
5120
5120
5120
5120
0
Power Level
47.0 dBmV
47.0 dBmV
47.0 dBmV
47.5 dBmV
47.0 dBmV
Modulation
QAM
QAM
QAM
QAM
OFDMA
Channel Type
ATDMA
ATDMA
ATDMA
ATDMA
TDMA

~30 minute error code snapshot

Codewords
Channel ID
44
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
193
194
Unerrored Codewords
21435769
95911500
95916483
95922007
95926991
95932049
95937072
95942611
95947929
95951240
95958689
95963995
95968694
95974043
95978592
95984619
95989279
95993621
95999061
96004172
96009699
96015129
96020999
96026563
96031694
96037038
96043071
96047824
96052969
96057313
96056464
96059502
21126883
21435769
Correctable Codewords
17535589
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
18402261
17535589
Uncorrectable Codewords
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

~5 day error code snapshot

CM Error Codewords
Channel ID 44 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 193 194
Unerrored Codewords 1099115319 986214421 986223204 986228218 986235154 986242166 986250309 986254539 986260429 986263496 986272026 986278417 986283872 986290465 986297851 986303274 986310421 986317475 986322834 986329964 986336604 986339945 986346308 986352491 986358923 986365340 986371162 986379088 986384329 986390842 986391534 986393592 1081919801 1099115319
Correctable Codewords 666309564 0 0 0 0 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 655830063 666309564
Uncorrectable Codewords 6206 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 29359828 6206

Official Employee

 • 

1.4K Messages

3 months ago

Thanks for taking the time to reach out, user_jli1791. To answer your questions directly it looks like there is something physical that's obstructing the clear signals being sent back and forth between us and your equipment. I would recommend a service tech but only after confirming what you found with the signal readings on my end. The only additional troubleshooting you could do is make sure everything is finger tight and swap out any pinched or severely bent coax cables with new ones. 

 

4 Messages

3 months ago

Thanks for your response, Antoine! I do see some pretty mild kinks in the indoor coax cable. I'll go ahead and swap it out before chasing this down further given that this sounds like a cable issue. I'll get that popped in tomorrow and validate if errors recover.

If issues continue, as far as getting readings on xfinity's end goes, how would I start that process? Is there a way that avoids the chatbot? :P

Official Employee

 • 

1.4K Messages

Yes! You can just reach back out to me here, and I'll get that service tech visit rolling for you. 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

4 Messages

Hi Antoine,

I swapped out the cable and still see pretty high correctable error rates. The below is a couple days of data, i swapped the cable and rebooted the modem.

With regards to:

only after confirming what you found with the signal readings on my end

What is the best way to do that confirmation prior to scheduling a service tech visit?

CM Error Codewords
Channel ID
44
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
193
194
Unerrored Codewords
1624963429
3745974898
3745982410
3745986188
3745990620
3745999455
3746003592
3746010331
3746014062
3746016998
3746026821
3746033488
3746038063
3746042759
3746049676
3746055963
3746059195
3746064688
3746069484
3746077151
3746083179
3746088272
3746094453
3746101158
3746106444
3746111351
3746116941
3746122887
3746128235
3746130891
3746135266
3746134045
1601969875
1624963429
Correctable Codewords
849058756
11
8
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
11
13
11
867511623
849058756
Uncorrectable Codewords
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

(edited)

Official Employee

 • 

1.7K Messages

Thank you for the update @user_jli1791! Upon sending us a direct message with your full name and full address, we can remotely troubleshoot your modem including a deeper look at the signals being sent to the device. To send a "Direct Message" to Xfinity Support:

 

Click "Sign In" if necessary

Click the "Direct Messaging" icon or  https://forums.xfinity.com/direct-messaging

Click the "New message" (pencil and paper) icon

The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there

 - As you are typing a drop-down list appears. Select "Xfinity Support" from that list

 - An "Xfinity Support" graphic replaces the "To:" line

Type your message in the text area near the bottom of the window

Press Enter to send it.

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

Expert

 • 

107.1K Messages

3 months ago

@user_jli1791 @XfinityAldrik 

Please circle back here and post any possible solutions for the issue here in these open public forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.

4 Messages

Thanks, sending DM, and yes I'll follow up here if there are any generally relevant findings.

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