U

Friday, September 27th, 2024 8:49 PM

XB8 - Downstream, upstream, & codewords tables missing stats 📉

Summary

The XB8's status page under under Gateway > Connection > XFINITY Network is missing stats for Downstream, Upstream, & Codewords tables, it displays zeros or blank columns. These were displaying correctly, up until 2024/09/24 after it rebooted itself.

* Internet performance did not change after this, but noticed the firmware version did change.

Example of the issue

Just one example, missing data changes when the page is refreshed.
Page from http://10.0.0.1/network_setup.jst

Downstream
Channel Bonding Value
Channel ID
9
1
2
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
37
Lock Status
Locked
Locked
Locked
Locked
Frequency
495 MHz
441 MHz
453 MHz
0
SNR
40.0 dB
40.5 dB
40.4 dB
38.3 dB
Power Level
0.5 dBmV
0.1 dBmV
0.1 dBmV
-3.5 dBmV
Modulation
256 QAM
256 QAM
256 QAM
OFDM

*Channel ID 0 is the Primary channel
Upstream
Channel Bonding Value
Channel ID
5
6
7
0
0
0
Lock Status
Locked
Locked
Locked
Frequency
10 MHz
16 MHz
22 MHz
Symbol Rate
2560
5120
5120
Power Level
35.8 dBmV
36.3 dBmV
37.0 dBmV
Modulation
QAM
QAM
QAM
Channel Type
ATDMA
ATDMA
ATDMA

CM Error Codewords
Channel ID
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
Unerrored Codewords
1059148606
1032394038
1035564917
1037412089
1039094226
1040837553
1042177306
1043606049
1044965898
1046293145
1047408245
1048500036
1049379438
1050338058
1051105705
1051865924
1052581077
1053302018
1053996946
1054636993
1055153030
1055688451
1056156465
986394638
1056848878
1057219208
1057586263
1057976592
1058276805
1058569925
1058865182
1059148606
Correctable Codewords
640
449
723
464
499
343
327
292
381
298
267
311
295
293
364
347
322
342
353
305
324
375
325
0
629
612
705
585
636
508
733
640
Uncorrectable Codewords
1493
419
1552
890
934
971
971
959
875
741
775
707
715
721
776
820
821
860
861
916
938
887
1017
609603
1316
889
886
962
1545
1027
1500
1493

Example 2

What stats are missing change almost everytime you refresh the page:

Full details of my XB8 Modem

HW Version:2.0
Vendor: Technicolor
BOOT Version: S1TC-3.81.21.97
Core Version: 1.0
Model: CGM4981COM
Product Type: XB8
Download Version: Prod_23.2_231009 & Prod_23.2_231009
Software Image Name: CGM4981COM_7.6p5s1_PROD_sey

"Software Image Names" I have seen the issue on:
  1. CGM4981COM_7.6p2s4_PROD_sey
  2. CGM4981COM_7.6p5s1_PROD_sey

My Xfinity Plan

Gigabit Extra "1200 Mbps"

Observed Channels (before issue)

The table used to show these columns on the page:

Downstream: 32 Channels (256 QAM + OFDM)
Upstream: 8 Channels (QAM)

Suspected Root Cause - Firmware Bug 🐛

I made no change to the XB8 myself. These stats were working fine before it rebooted itself overnight then I observed it went from firmware version "Prod_22.2_d31 & Prod_22.2" to "Prod_23.2_231009 & Prod_23.2_231009", so this almost certainly seems like a firmware bug.

* I am guessing "Software Image Name" changed too, but I didn't happen catch what the old name was.

Troubleshooting 

* Tried rebooting the XB8 twice from the Troubleshooting > Reset / Restore Gateway page

* Waited a few minutes after rebooting before checking the stats page

* Refreshed the page many times, most of the noted stats are missing

* Factory reset

   - Went to "Troubleshooting > Reset / Restore Gateway"  then pressed "Restore Factory Settings".

* Unplugging the XB8 for 30 seconds
* Different browsers and computers / devices
  - WIndows 11 - Chrome & Firefox

  - Windows 10 - Chrome

  - Android - Chrome
  - macOS - Safari
* Viewed on ethernet and Wifi
* Inspected the HTML - Fields that are missing data are really not in the HTML

    - In the table the <td> tags contain <div> tags, but they have 0 or no string value at all. Stats that are visible in the browser are in the HTML, so I am looking at the correct spot. So in conclusion, not a browser rendering issue.

* Firmware rollback - Can't attempt, Xfinity support said "Unfortunately, we don't have a way to rollback the firmware from our end..."

Reports of this bug

About 10 people in total seem to have reported this bug:

  1. https://www.dslreports.com/forum/r33952035-Signals-Lost-Internet-and-Now-only-one-Upstream-Channel
  2. https://www.dslreports.com/forum/r33959469-XB8-down-up-channels-disapearing-then-reappearing
  3. https://www.dslreports.com/forum/r33227126-Next-Gateway-XB8-Technicolor-CGM4981COM-Wi-Fi-6E~start=1020
    1. https://www.dslreports.com/forum/r33951511-
    2. https://www.dslreports.com/forum/r33951520-
    3. https://www.dslreports.com/forum/r33937936-
  4. https://www.reddit.com/r/Comcast_Xfinity/comments/1fix8vm/xfinity_hiding_modem_stats/
  5. Two+ Xfinity Comcast Support Contractors / Employees (they noted this in my chat with them)
  6. And this post + another in the replies section here.

Work Around - Bridge Mode

If you have your own router you can enable "Bridge Mode" on the XB8, then all these stats correctly show.

* Normally, a setting like this shouldn't effect the stats, but again, thinking this is just some odd firmware bug.
* Confirmed this on firmware "CGM4981COM_7.6p5s1_PROD_sey".

Status

Current - Ticket open with the "Engineering team" (2024/10/08)

Two Xfinity support employees were able to reproduce the issue and escalated it to the "Advanced Repair Team". Then they escalated it to the "Engineering team" on 2024/10/08.

History

2024/10/04

On 2024/10/03, I chatted with Xfinity and they were able to reproduce this issue as well. They opened a ticket with the "Advanced Repair Team" so they can look into the issue.

In my chat with support they also noted these stats might be moved to the "Xfinity App", but I personally doubt that, as the app is more high-level / customer friendly where these stats are more "prosumer" focused. I believe Xfinity support just said that as it's probably Xfinity's plan to move more stuff into the app, but they said may/might as they are probably don't know exactly what will be moved.

As a prosumer myself I want these stats to stay accessible from the Cable device itself for two reasons:

  1. If the connection is bad enough the device won't be able to upload them to Xfinity's server, nor would my devices be able to get a internet connection to fetch the stats through the app to their server either.
  2. I want keep my automated monitoring of these stats. I use this to know if my internet hiccups are related to coax RF noise or power levels or something else.

2024/10/05

Support got back to me but "Advanced Repair Specialists" could not reproduce the issue. They asked me to try different web browsers (I already put this in my post here) and I let them know that Xfinity support people "XfinityPersonA" and "XfinityPersonB" can reproduce the issue so suggested those to teams might be able to help reproduce faster internally. However I told them I was happy to try more things.

I also noted:

Since your "Advanced Repair Specialists" could not reproduce but those Xfinity support employees can (as well as me, and a few others) there must be some differences in the test setup; such as firmware version, hardware revision, or DOCSIS provisioning.

2024/10/07

A new firmware, CGM4981COM_7.6p5s1_PROD_sey, was discovered in the wild and I asked Xfinity support if they could push a DOCSIS command down to install it on my XB8, to see if it addresses the issue. Xfinity 's support team attempted to send a provisioning signal and rebooted the XB8. (I assume they did this to see if this would trigger the automatic update). They provisioning twice with no luck, so they reached out to the Advanced Repair Team" to see if they can update me to this new firmware.

2024/10/08

Xfinity support let me know they sent the issue over to the "Engineering team" to take a look a this.

2024/10/11

Firmware was updated to CGM4981COM_7.6p5s1_PROD_sey around 3am, however it did not fix this issue. I let support know this detail.

2024/10/13

Found that the XB8's "Bridge Mode" is a work around (added a section above with more details). Also I let the Xfinity Support team know.

Visitor

 • 

19 Messages

1 month ago

I have had this same issue with 2 different XB8 modems as well. There is no way to fix it until they do another firmware update but, who knows when that will be,

8 Messages

@user_dd7863 have you tried "Restore Factory Settings"? Was thinking of giving this a try but it's a pain for me to set thing back up so I have been holding out on this.

Update: I tried the factory reset, didn't help.

(edited)

Visitor

 • 

19 Messages

@user_xn7m4m​ I did it with my last modem and nothing so, I got my old modem went to the comcast office and turned it in for a new one. It was fine for a day, it then updated and bricked the stats page again. They really need to get their stuff together.

Official Employee

 • 

1.7K Messages

@user_dd7863 Thank you for reaching out to let us know that your modem stats aren't showing up. I'd like to troubleshoot this issue with you and open a ticket for our Advanced Repair team if we're unable to resolve the issue together. 

Please send a direct message by clicking the chat icon in the upper right corner of the page, click on the pen and paper icon, then enter “Xfinity Support” in the “To” section. Please include your name and address and I'll be happy to help.

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

Visitor

 • 

19 Messages

@XfinityEmilyB​ Nothing against you Emily but, this is obviously a firmware issue. This didn't happen before this current firmware update. I even got a new XB8 modem from the Xfinity store near me and the stats page was perfectly fine until it updated it's firmware the next day. Xfinity really needs to talk to the maker of the modem and either revert the firmware update for everyone or fix it in a new version. 

8 Messages

There is also two other users who also have this issue on the Comcast_Xfinity subreddit, posted on 2024/09/17:

https://www.reddit.com/r/Comcast_Xfinity/comments/1fix8vm/xfinity_hiding_modem_stats/

Based on the information we have so far in these 2 threads I highly suspect a firmware bug as well.
* The only other thing comes to mind is maybe some bad provisioning, but that seems unlikely.

@XfinityEmilyB could someone at Xfinity also test this with the firmware versions listed here to confirm if you're seeing the issue internally or not?

(edited)

25 days ago

I as well as of last night now have this graphical bug where the info shows 0's for all the channels and refreshing several times has a few show up again. I'm on CGM4981COM_7.3p7s1_PROD_sey on the XB8-T

Official Employee

 • 

2.7K Messages

@GhostlyLurker Thank you for taking the time to reach out to us here on our Xfinity Forums. Just to confirm, are you still experiencing this issue? Is it affecting your services? The more information you can provide us, the better we will be able to help.

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

8 Messages

23 days ago

I found a work around, if you have your own router you can enable "Bridge Mode" on the XB8.

* When using your own router, it's recommend you enable this anyway, for best performance (and to avoid double NAT).
* Normally a setting like this shouldn't affect these stats, but again, thinking this is just some odd firmware bug. Perhaps a bug with the XB8's "router code" causing a bug with the "cable modem code".

I confirmed this work around works on the "CGM4981COM_7.6p5s1_PROD_sey" firmware, but might be a work around for other versions too.

While most people who care about these stats probably have their own router, not everyone does. Also this should work regardless of the "Bridge Mode" setting, so this a bug. Lastly, even if you have your own router you may want to go back to the XB8's normal mode if you have issues and want to debug something, these stats missing makes things harder.

(edited)

Official Employee

 • 

1.2K Messages

This si great that you found this workaround

user_xn7m4m! We will leave any existing tickets open for this issue until we have a full solution. 

 

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
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