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Forum Discussion
DudeRides
May 20, 2026Aspirant
Xfinity Says I Need To Replace My CM3000
Hello,
A couple of days ago I had a technical support call with Xfinity regarding a streaming issue. During the call, they checked modem status and claimed that the modem was generating errors. They scheduled a tech visit to assess. Since I run my own CM3000 modem, the only thing the tech checked was line quality. The quality was determined to be good, all the way into the final connection to the modem. The tech suggested that the modem was bad.
I looked at the system log for the modem last night, and indeed there are a lot of critical messages, including SYNC errors and T4 time out errors.
Does the community agree that the CM3000 is suspect, or should I do more assessment of the line in?
Note: About a year ago the house next door was struck by lightning. It immediately cooked my TPLink router. The CM3000 seemed to not be affected, but maybe it was but it was able to work just well enough to get by?
Thank you.
7 Replies
- CrimpOnGuru - Experienced User
Here's hoping that the information helps place the blame squarely on the modem or the cable. If it does not....
Perhaps a silly question..... If you have Xfinity install a modem, how long are you required to keep it?
I see two obvious ways to settle the question of "is it the modem or the cable?"
- Spend over $150 to buy a new Xfinity compatible modem
https://www.xfinity.com/support/internet/customerowned
If the streaming problems go away and the new modem does not report the same errors as the existing modem, then the original modem was probably bad.
If the streaming problems remain and the new modem reports the same sort of errors as the original modem, it is probably the cable. - Have Xfinity install their modem (at about $15/month).
If the streaming problems remain with the Xfinity modem, then the problem is with the cable and Xfinity needs to fix it.
If the streaming problems go away, then the original modem was bad and you now get to make the same decision as before. "Is it better to spend $15/month to rent an Xfiniity modem or to buy my own modem?"
I would probably go with, "install an Xfinity modem" to save the potential hassle of returning a modem if it turns out that the cable was bad.
- Spend over $150 to buy a new Xfinity compatible modem
- DudeRidesAspirant
Do you need a screenshot of the entire page, scrolling the page, or only a particular spec or message?
- FURRYe38Guru - Experienced User
You can copy the text data and paste it into your post.
Images copy and paste isn't working currently.
Lets check the signal and data first before doing anything else.
DudeRides wrote:
Do you need a screenshot of the entire page, scrolling the page, or only a particular spec or message?
- DudeRidesAspirant
Downstream Bonded Channels Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 20 525000000 Hz 7.2 dBmV 43.6 dB 1136 1242 2 Locked QAM256 1 405000000 Hz 6.4 dBmV 43.5 dB 2398 2922 3 Locked QAM256 2 411000000 Hz 6.9 dBmV 43.3 dB 2652 2858 4 Locked QAM256 3 417000000 Hz 6.8 dBmV 43.7 dB 2443 2824 5 Locked QAM256 4 423000000 Hz 6.7 dBmV 43.6 dB 2359 2673 6 Locked QAM256 5 429000000 Hz 6.9 dBmV 43.7 dB 2162 2658 7 Locked QAM256 6 435000000 Hz 6.9 dBmV 43.6 dB 2236 2520 8 Locked QAM256 7 441000000 Hz 6.5 dBmV 43.4 dB 1960 2564 9 Locked QAM256 8 447000000 Hz 6.4 dBmV 43.3 dB 2093 2479 10 Locked QAM256 9 453000000 Hz 6.5 dBmV 43.3 dB 2019 2425 11 Locked QAM256 10 459000000 Hz 6.6 dBmV 43.4 dB 2075 2329 12 Locked QAM256 11 465000000 Hz 6.6 dBmV 43.3 dB 1922 2372 13 Locked QAM256 12 471000000 Hz 6.5 dBmV 43.2 dB 1983 2311 14 Locked QAM256 13 477000000 Hz 6.5 dBmV 43.2 dB 1911 2360 15 Locked QAM256 14 483000000 Hz 6.6 dBmV 43.3 dB 1738 2150 16 Locked QAM256 15 489000000 Hz 6.6 dBmV 43.2 dB 1732 2161 17 Locked QAM256 16 495000000 Hz 6.6 dBmV 43.2 dB 1816 2092 18 Locked QAM256 17 507000000 Hz 7.1 dBmV 43.4 dB 1459 2016 19 Locked QAM256 18 513000000 Hz 7.5 dBmV 43.7 dB 1526 1906 20 Locked QAM256 19 519000000 Hz 7.4 dBmV 43.6 dB 1530 1806 21 Locked QAM256 21 531000000 Hz 7.2 dBmV 43.5 dB 1341 1752 22 Locked QAM256 22 537000000 Hz 6.8 dBmV 43.3 dB 1347 1694 23 Locked QAM256 23 543000000 Hz 6.2 dBmV 43.0 dB 1239 1780 24 Locked QAM256 24 549000000 Hz 5.6 dBmV 42.6 dB 1345 1689 25 Locked QAM256 25 555000000 Hz 5.5 dBmV 42.5 dB 1218 1625 26 Locked QAM256 26 561000000 Hz 5.8 dBmV 42.7 dB 1235 1560 27 Locked QAM256 27 567000000 Hz 6.3 dBmV 42.9 dB 1062 1631 28 Locked QAM256 28 573000000 Hz 6.4 dBmV 42.9 dB 1092 1527 29 Locked QAM256 29 579000000 Hz 6.3 dBmV 42.7 dB 966 1462 30 Locked QAM256 30 585000000 Hz 6.3 dBmV 42.7 dB 954 1434 31 Locked QAM256 31 591000000 Hz 6.5 dBmV 42.7 dB 961 1415 32 Locked QAM256 32 597000000 Hz 6.7 dBmV 42.8 dB 934 1380 Upstream Bonded Channels Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power 1 Locked ATDMA 5 1280 Ksym/sec 39600000 Hz 44.0 dBmV 2 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 46.5 dBmV 3 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 46.5 dBmV 4 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 46.5 dBmV 5 Locked ATDMA 1 5120 Ksym/sec 35600000 Hz 46.5 dBmV 6 Not Locked Unknown 0 0 0 0.0 dBmV 7 Not Locked Unknown 0 0 0 0.0 dBmV 8 Not Locked Unknown 0 0 0 0.0 dBmV Downstream OFDM Channels Channel Lock Status Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier Number Range Unerrored Codewords Correctable Codewords Uncorrectable Codewords 1 Locked 0 ,1 ,2 ,3 193 690000000 Hz 5.48 dBmV 41.8 dB 1228 ~ 2867 2921873759 1604952562 2848 2 Not Locked 0 0 0 Hz 0 dBmV 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
- FURRYe38Guru - Experienced User
Lets take a look at the modem signal and event log on from the modem.
Please post a copy and paste of the modems connection status and event log page.
Any Criticals, Errors or Warnings seen in the event logs needs to be reviewed and resolved by the ISP. Indicates a signal issue on the ISP line up to the modem.
ISP is known for making false claims so you'd get or rent something from them...