Visitor

 • 

10 Messages

Monday, September 8th, 2025

Internet Issues

Hello, for the last year or so I’ve been experiencing severe intermittent latency spikes while gaming and working from home. The connection is stable most of the time (~20–25ms to Google DNS), but every few minutes I get 1–2 second bursts of extremely high latency (2000–2700ms) before it returns to normal. This makes online applications and games unusable. I have been told everything is fine and the issue is on my end my I have done everything and it remains the same.

I ran extended WinMTR tests to verify:

Local router is clean (no loss, no latency).

The issue begins at Comcast’s first hop: 96.120.112.157. That hop shows spikes of 2000–2700ms worst-case, average ~15–26ms.

The spikes ripple through to all subsequent hops.

Final destination (Google DNS 8.8.8.8) is mostly stable, but the spikes are disruptive.

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Expert

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113.3K Messages

5 days ago

What do the modem's signal status values look like ? Try getting them here; http://192.168.100.1 or here http://10.0.0.1 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.


What is the exact make and model number of the modem / gateway device ?

Visitor

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10 Messages

Apologies I was at the store I could not get a hold of these there, here they are.
Current Modem: CGM4981COM



Downstream

Chan | Frequency -| Power       | SNR     |Modulation| Lock Status

-------|------------|-------------|---------|------------|------------

13      | 507 MHz   | 1.1 dBmV  | 42.2 dB | 256 QAM | Locked

10      | 483 MHz   | 1.5 dBmV  | 41.3 dB | 256 QAM | Locked

11      | 489 MHz   | 1.4 dBmV  | 40.5 dB | 256 QAM | Locked

12      | 495 MHz   | 1.2 dBmV  | 41.4 dB | 256 QAM | Locked

14      | 513 MHz   | 1.2 dBmV  | 39.8 dB | 256 QAM | Locked

15      | 519 MHz   | 1.1 dBmV  | 37.1 dB | 256 QAM | Locked

16      | 525 MHz   | 1.0 dBmV  | 39.4 dB | 256 QAM | Locked

17      | 531 MHz   | 1.0 dBmV  | 41.8 dB | 256 QAM | Locked

18      | 537 MHz   | 1.0 dBmV  | 33.8 dB | 256 QAM | Locked

19      | 543 MHz   | 1.0 dBmV  | 37.7 dB | 256 QAM | Locked

20      | 549 MHz   | 1.1 dBmV  | 41.3 dB | 256 QAM | Locked

21      | 555 MHz   | 1.2 dBmV  | 41.8 dB | Unknown | Locked

22      | 561 MHz   | 1.2 dBmV  | 41.5 dB | 256 QAM | Locked

23      | 567 MHz   | 1.6 dBmV  | 41.5 dB | 256 QAM | Locked

24      | 573 MHz   | 1.7 dBmV  | 41.1 dB | 256 QAM | Locked

25      | 579 MHz   | 1.7 dBmV  | 42.0 dB | 256 QAM | Locked

26      | 585 MHz   | 1.8 dBmV  | 41.9 dB | 256 QAM | Locked

27      | 591 MHz   | 1.9 dBmV  | 41.9 dB | 256 QAM | Locked

28      | 597 MHz   | 2.0 dBmV  | 42.0 dB | 256 QAM | Locked

29      | 603 MHz   | 2.0 dBmV  | 41.4 dB | 256 QAM | Locked

30      | 609 MHz   | 1.9 dBmV  | 41.1 dB | 256 QAM | Locked

31      | 615 MHz   | 1.8 dBmV  | 41.7 dB | 256 QAM | Locked

32      | 621 MHz   | 1.8 dBmV  | 41.6 dB | 256 QAM | Locked

33      | 627 MHz   | 1.7 dBmV  | 41.0 dB | 256 QAM | Locked

34      | 633 MHz   | 1.8 dBmV  | 41.3 dB | 256 QAM | Locked

35      | 639 MHz   | 2.0 dBmV  | 41.3 dB | 256 QAM | Locked

36      | 645 MHz   | 2.0 dBmV  | 41.7 dB | 256 QAM | Locked

37      | 651 MHz   | 2.4 dBmV  | 41.0 dB | 256 QAM | Locked

38      | 657 MHz   | 2.5 dBmV  | 41.7 dB | 256 QAM | Locked

0       | 690 MHz   | 3.0 dBmV  | 41.0 dB | OFDM    | Locked


Upstream
Chan| Frequency | Power         | Symbol Rate| Modulation | Channel Type | Lock Status

------|-------------|-------------|-------------|---------------|----------------|------------

1       | 35 MHz     | 46.0 dBmV | 5120           | QAM             | ATDMA        | Locked

2       | 29 MHz    | 46.0 dBmV | 5120            | QAM             | ATDMA        | Locked

3       | 22 MHz    | 45.3 dBmV | 5120            | QAM             | ATDMA        | Locked

4       | 16 MHz    | 44.5 dBmV | 5120            | QAM             | ATDMA        | Locked

5       | 39 MHz    | 46.0 dBmV | 1280            | QAM             | ATDMA        | Locked



(edited)

Expert

 • 

113.3K Messages

4 days ago

The signal status values were good at that snapshot in time. Please also post the modem's RF error log entries in their entirety (copy and paste all of the text) but redact the CM and the CMTS MAC addresses for privacy or else the forum bot will not allow your post to be seen publicly.

Visitor

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10 Messages

I am looking for it, does not seem to be avail,  what I can pull up is event logs that only pull up wifi activity, and CM Error Codewords, let me know if you want those. This is a rented modem so I don't know if I can pull those up. I can reconnect my previous modem to see what they are.

(edited)

Visitor

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10 Messages

CM Error Codewords
Channel ID 
13
10
11
12
14
15
15
17
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Unerrored Codewords 
3099539810
2114569084
2114614329
2114644240
2114651810
2048836583
2114744940
2114758768
4181327650
533125434
4175088131
0
4175159152
4175179803
4175177630
4175202206
4175243419
4175235580
4175255751
4175272902
3520642261
3520665198
3520668277
3520681057
3520696341
3520698663
3520717633
3520726470
3520729214
3520748982
3520753583
3099539810
Correctable Codewords 
1789589777
359
416
455
33458
2843285
1192
428
355004812
1543554
304
303
279
257
278
0
205
219
149
188
169
203
209
226
273
329
391
522
571
731
821
1789589777
Uncorrectable Codewords 
11375
101
110
163
156
283560
385
140
6860438
1281
56
37
45
32
1
25
28
0
15
0
21
29
0
123
129
291
515
903
1215
1880
2124
11375

Expert

 • 

113.3K Messages

4 days ago

The RF error log reporting seems to be disabled for some. The wifi activity / router logs would be unhelpful.  The CM Error Codewords may be helpful.

(edited)

Visitor

 • 

10 Messages

Sent they are above your post.

Official Employee

 • 

2.1K Messages

Thank you for reaching out here. I will be happy to look into any issue with your internet. Can you send me a direct message with the full name and complete address for your service? 

To send a direct message [private message]:

   Click the "Direct Message" 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

 • 

113.3K Messages

4 days ago

A few of the downstream channels have a fairly large amount of uncorrectable bit errors. Perhaps there is noise ingress into the line(s) /  an upstream channel / return path impairment somewhere.


There are other signal stat values 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 (The Digital Care Team) who are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and those upstream receive signal stats.


You should get a reply here in your topic. Good luck !

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