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MootValue
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8 Messages

Saturday, August 3rd, 2024 9:02 PM

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Intermittent modem reconnection

Ever since joining Xfinity, several times a day, my modem (an Arris SURFboard S33v2) loses connection to Xfinity and goes through a light cycle of solid amber to blinking green ("channel search") to blue ("online in DOCSIS 3.1 mode"). I'm not certain what the issue is, and have found conflicting information on this modem working or not working with Xfinity.

I don't mind replacing it with a different modem if that's what it takes, but I'm not sure if that's likely to fix the problem or not, and would appreciate it if anyone has any insight on what the source of the problem might be.

Things tried:

  • Resetting modem
  • Replacing splitter with same model (BDS103H, modem connected to -7db)
  • Connecting modem directly to incoming coax line
Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
20 Locked QAM256 501000000 Hz 0 dBmV 43 dB 176 788
1 Locked QAM256 387000000 Hz -1 dBmV 42 dB 753 3869
2 Locked QAM256 393000000 Hz -1 dBmV 42 dB 2221 8795
3 Locked QAM256 399000000 Hz -1 dBmV 42 dB 3433 6867
4 Locked QAM256 405000000 Hz -1 dBmV 42 dB 4442 5977
5 Locked QAM256 411000000 Hz -1 dBmV 42 dB 3112 4808
6 Locked QAM256 417000000 Hz -1 dBmV 42 dB 1883 1094
7 Locked QAM256 423000000 Hz -1 dBmV 42 dB 1878 5180
8 Locked QAM256 429000000 Hz -1 dBmV 42 dB 1491 3910
9 Locked QAM256 435000000 Hz -1 dBmV 43 dB 1410 4600
10 Locked QAM256 441000000 Hz -1 dBmV 43 dB 787 2009
11 Locked QAM256 447000000 Hz 0 dBmV 43 dB 2359 10885
12 Locked QAM256 453000000 Hz 0 dBmV 43 dB 1251 4892
13 Locked QAM256 459000000 Hz 0 dBmV 43 dB 1216 5281
14 Locked QAM256 465000000 Hz 0 dBmV 43 dB 1133 4926
15 Locked QAM256 471000000 Hz 0 dBmV 43 dB 776 3095
16 Locked QAM256 477000000 Hz 0 dBmV 43 dB 1233 5107
17 Locked QAM256 483000000 Hz 0 dBmV 43 dB 562 2174
18 Locked QAM256 489000000 Hz 0 dBmV 43 dB 1870 8897
19 Locked QAM256 495000000 Hz 0 dBmV 43 dB 778 3593
21 Locked QAM256 507000000 Hz 0 dBmV 43 dB 1020 4670
22 Locked QAM256 513000000 Hz 0 dBmV 43 dB 2542 12376
23 Locked QAM256 519000000 Hz 0 dBmV 43 dB 1194 5681
24 Locked QAM256 525000000 Hz 0 dBmV 43 dB 1098 5203
25 Locked QAM256 531000000 Hz 0 dBmV 43 dB 1035 4938
26 Locked QAM256 537000000 Hz 0 dBmV 43 dB 1074 5274
27 Locked QAM256 543000000 Hz 0 dBmV 43 dB 1062 5049
28 Locked QAM256 549000000 Hz 0 dBmV 43 dB 970 4706
29 Locked QAM256 555000000 Hz 0 dBmV 43 dB 1264 5764
30 Locked QAM256 561000000 Hz 0 dBmV 43 dB 2376 11708
31 Locked QAM256 567000000 Hz 0 dBmV 43 dB 900 3798
32 Locked QAM256 573000000 Hz 0 dBmV 43 dB 1139 5523
193 Locked OFDM PLC 722000000 Hz 0 dBmV 43 dB 16495824 3
194 Locked OFDM PLC 957000000 Hz -5 dBmV 40 dB 7347557 421


Upstream Bonded Channels
Channel ID Lock Status US Channel Type Frequency Width Power
17 Locked SC-QAM 16400000 Hz 6400000 50.0 dBmV
18 Locked SC-QAM 22800000 Hz 6400000 50.0 dBmV
19 Locked SC-QAM 29200000 Hz 6400000 49.3 dBmV
20 Locked SC-QAM 35600000 Hz 6400000 50.0 dBmV

Date Time Event Level Description
31/12/1969
16:00:16		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:20		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:22		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:22		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
2/8/2024
23:06:32		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
2/8/2024
23:06:45		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:16		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:19		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:20		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:20		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:21		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:34		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:34		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
2/8/2024
23:46:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
2/8/2024
23:46:37		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:15		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:19		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
3/8/2024
01:47:16		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
3/8/2024
01:47:30		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:15		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:19		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:21		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
3/8/2024
03:03:36		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
3/8/2024
03:03:51		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:15		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:19		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
3/8/2024
04:11:30		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
3/8/2024
04:11:44		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:15		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:20		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
3/8/2024
04:25:29		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
3/8/2024
04:25:45		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:15		 3 CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.
31/12/1969
16:00:19		 3 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[redacted];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
31/12/1969
16:00:21		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
31/12/1969
16:00:22		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
31/12/1969
16:00:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
31/12/1969
16:00:28		 6 Honoring MDD; IP provisioning mode = IPv6
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
31/12/1969
16:00:36		 3 CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
3/8/2024
10:27:22		 3 CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
3/8/2024
10:27:28		 6 DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
3/8/2024
10:27:29		 6 DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[redacted];CMTS-MAC=[redacted]CM-QOS=1.1;CM-VER=3.1;
3/8/2024
10:27:37		 3 UCD invalid or channel unusable;CM-MAC=[redacted];CMTS-MAC=[redacted];CM-QOS=1.1;CM-VER=3.1;
3/8/2024
12:24:51		 3 Successful LAN WebGUI login from [redacted] on 24/08/03 at 12:24 PM.
Information
Standard Specification Compliant DOCSIS 3.1
Hardware Version V1.0
Software Version TB01.03.001.10_012022_212.S3
Cable Modem MAC Address [redacted]
Serial Number [redacted]

Question

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Updated 

3 months ago

 • Edited

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Accepted Solution

MootValue

8 Messages

3 months ago

There have been no issues with the Xfinity Gateway, so looks like my modem was the problem. Thanks again for the help with this!

1

0

XfinityBrianH

Official Employee

 • 

948 Messages

 

MootValue Thank you so much for following up with us to let us know the outcome! Please reach out to us again if you have any other concerns we can assist you with. 

 

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

3 months ago

0

EG

Expert

 • 

107.2K Messages

4 months ago

The upstream power is too high / almost out of spec, and it may be intermittently fluctuating even higher to out-of-spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Try putting the modem on the -3,5 dB port instead.

Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.


Good luck with it !

(edited)

2

0

MootValue

8 Messages

Thanks very much for your answer!

I swapped to the -3.5 dB port and the upstream channels now look like this:

Upstream Bonded Channels
Channel ID Lock Status US Channel Type Frequency Width Power
17 Locked SC-QAM 16400000 Hz 6400000 46.5 dBmV
18 Locked SC-QAM 22800000 Hz 6400000 46.5 dBmV
19 Locked SC-QAM 29200000 Hz 6400000 46.0 dBmV
20 Locked SC-QAM 35600000 Hz 6400000 46.5 dBmV


I'll let it run and see if I still get disconnects in the next day or two. Other than that, the connections and cables look good, and there are no extraneous splitters.

4 months ago

0

MootValue

8 Messages

Also, I'll mention that the modem is the only thing actually connected to coax; the splitter has all three ports connected to wall jacks, but two of the jacks have nothing connected.

4 months ago

0

EG

Expert

 • 

107.2K Messages

4 months ago

Now there is a bit of wiggle room ! If the other wall jacks are not being used they should be disconnected and the splitter should not be used (a direct run to the modem). You'll gain even more wiggle room. 

0

0

MootValue

8 Messages

4 months ago

It looks like the -3.5 dB port didn't do it. As for the direct run to the modem, that's one of the things I tried before—I had it connected directly to the incoming line with nothing in between. So, sounds like I need a technician.

Is there any way to request a technician visit without having to go through tier 1 support?

0

0

EG

Expert

 • 

107.2K Messages

4 months ago

I'm going to escalate this to the Comcast corporate employees (The Digital Care Team) who are available to these boards. They will be able to arrange a tech visit for you. You should get a reply here in your topic. Good luck and please post back here with how it turns out.

(edited)

0

0

MootValue

8 Messages

3 months ago

I had a tech visit, he found no issues with my connection, and other apartments in my building haven't been having problems. He thinks it's the modem, which I'm fine with replacing as the next step. He recommended buying Netgear.

As long as I'm buying a new modem, is it particularly worthwhile to buy a modem on the list of recommended devices (as opposed to the list of compatible devices)?

0

0

MootValue

8 Messages

3 months ago

Xfinity support reached out to offer to credit a month of Xfinity Gateway rental so I can see if the problem persists before paying out of pocket for a new modem—I'm going to go with that first.

0

0

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