Cable connection issues on Comcast/Xfinity with CBR750

Hello. I am using the Orbi CBR750 modem/router mesh combo with one RBS750 satellite, and Comcast/Xfinity as my ISP. Starting this morning, I have been experiencing strange issues with my connection. For reference, I bought the Orbi kit on 11-25-2022 and the date of my last config file is 12-4-2022, which until today was the last time I made any configuration changes. (I can't tell you what the previously installed FW was before today, but this might help.)

My network had been working fine from 12-4-2022 until just today 1-23-2023 with no outages or slowdowns that I am aware of. But suddenly this morning when I woke up, my phone wouldn't connect to WiFi, nor would my smart TV, nor would my PlayStation, all of which use the 5GHz WiFi channel on my network. Weirdly enough, devices that use only 2.4GHz (like the Nintendo Switch) seemed unaffected. So the first thing I did was to log in to the online gateway on my desktop and reboot everything. After doing so, I also checked to see if there were any firmware updates, which there were, so I installed those as well, before rebooting everything again. So now my current firmware version on the CBR750 is V4.6.14.4 and the FW version on my RBS750 is V4.6.14.3. However, right after the firmware update, I noticed something curious when returning to the Basic Home screen. Namely, under "Cable Connection" there is now a yellow caution saying "Status: Poor." This, despite everything seemingly working normally again. When I click on the page for details, it says something about my Downstream signal being weak, which I've never seen before. Nothing at all about my setup has changed from 7 weeks ago when I first set up my network, save for this new firmware update today.

I have rebooted my modem several times, to no avail. I ran ipconfig and did release/renew as admin. I have also disconnected all wires, including power, coaxial, and Ethernet, and then reconnected them again. There is no damage to any of the cords, everything is pristine.  I am not using any splitters, attenuators, or adapters of any kind that could weaken the signal.. My coaxial cable connection goes directly from the wall to my modem with nothing in between.

For what it's worth, my WiFi does seem to work for now. Neverthless, this caution message worries me, so I tried calling Comcast/Xfinity to see if they might be able to re-provision the modem, because in the past when I had issues on another Netgear device, this always seemed to fix things if a simple reboot didn't already. However, when I called them they said they were unable to detect an attached device. From their end, it looks like I do not have a modem connected! Thus, they cannot send a reset signal. They said it could possibly be a line issue, but they seemed baffled as well. They scheduled me for an appointment with a technician this Thursday.

What's weird is, aside from these error messages, everything is pretty much working fine. That is, the devices that couldn't connect this morning are now connected and working again. However, the gateway page still says "Cable Connection Status: Poor" and my ISP still can't detect my modem, even though it's online. It shows the status as being disconnected, even though it clearly isn't.

As an aside, I've just read the note that had been pinned to the forum a few days ago by user "FURRYe38" about a known issue with Comcast/Xfinity apparently splitting its 1Gbps speed tier into either 800Mbps or 1.2Gbps in some areas and how this is causing issues for some users, but that isn't the case with my account. When I called and spoke with a Comcast/Xfinity today they were able to confirm that I still have 1Gbps down and 20Mbps up as my active plan, and the tier has not been split way in my area. So that doesn't seem to be the source of the problem in my case. Logs incoming...

Here is the information shown on the "Cable Connection" page:

Cable Diagnostic
Status: Poor
Action:
[Downstream Power Level]
Try these actions (Click the Refresh button after each step):
1) Make sure the coaxial cable is tightly connected.
2) Remove any unnecessary splitters.
3) Replace any required splitters.
4) Contact your service provider for troubleshooting help.
Internet Access:
Downstream Status:
Upstream Status:

Refresh Save Cable Diagnostic Info
Advanced Information
Frequency Start Value
This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.
Starting Frequency
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 507000000 Hz Locked
Connectivity State Ok Operational
Boot State Ok Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectable
1 Locked QAM 256 14 489000000 Hz 9.6 dBmV 40.3 dB 0 0
2 Locked QAM 256 15 495000000 Hz 9.6 dBmV 40.3 dB 0 0
3 Locked QAM 256 16 501000000 Hz 9.8 dBmV 40.3 dB 0 0
4 Locked QAM 256 17 507000000 Hz 9.8 dBmV 40.3 dB 0 0
5 Locked QAM 256 18 513000000 Hz 9.9 dBmV 40.3 dB 0 0
6 Locked QAM 256 19 519000000 Hz 10.0 dBmV 40.9 dB 2 0
7 Locked QAM 256 20 525000000 Hz 10.0 dBmV 40.3 dB 0 0
8 Locked QAM 256 21 531000000 Hz 10.0 dBmV 40.3 dB 0 0
9 Locked QAM 256 22 537000000 Hz 10.0 dBmV 40.3 dB 0 0
10 Locked QAM 256 23 543000000 Hz 10.0 dBmV 40.3 dB 0 0
11 Locked QAM 256 24 549000000 Hz 10.0 dBmV 40.3 dB 0 0
12 Locked QAM 256 25 555000000 Hz 10.0 dBmV 40.3 dB 0 0
13 Locked QAM 256 26 561000000 Hz 10.0 dBmV 40.9 dB 0 0
14 Locked QAM 256 27 567000000 Hz 10.0 dBmV 40.3 dB 0 0
15 Locked QAM 256 28 573000000 Hz 10.1 dBmV 40.3 dB 0 0
16 Locked QAM 256 29 579000000 Hz 10.1 dBmV 40.3 dB 0 0
17 Locked QAM 256 30 585000000 Hz 10.4 dBmV 38.9 dB 0 0
18 Locked QAM 256 31 591000000 Hz 10.4 dBmV 40.9 dB 0 0
19 Locked QAM 256 32 597000000 Hz 10.5 dBmV 40.3 dB 0 0
20 Locked QAM 256 33 603000000 Hz 10.9 dBmV 40.3 dB 0 0
21 Locked QAM 256 34 609000000 Hz 10.9 dBmV 40.3 dB 0 0
22 Locked QAM 256 35 615000000 Hz 11.0 dBmV 40.3 dB 0 0
23 Locked QAM 256 36 621000000 Hz 11.3 dBmV 38.9 dB 0 0
24 Locked QAM 256 37 627000000 Hz 11.3 dBmV 38.9 dB 0 0
25 Locked QAM 256 38 633000000 Hz 11.3 dBmV 38.9 dB 0 0
26 Locked QAM 256 39 639000000 Hz 11.1 dBmV 38.9 dB 0 0
27 Locked QAM 256 40 645000000 Hz 11.1 dBmV 38.9 dB 0 0
28 Locked QAM 256 41 651000000 Hz 11.0 dBmV 38.9 dB 0 0
29 Locked QAM 256 42 657000000 Hz 11.0 dBmV 38.9 dB 0 0
30 Locked QAM 256 43 663000000 Hz 11.0 dBmV 40.3 dB 0 0
31 Locked QAM 256 44 669000000 Hz 11.0 dBmV 40.3 dB 0 0
32 Not Locked N/A N/A 0 Hz 0.0 dBmV 0.0 dB 0 0
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 43.5 dBmV
2 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 43.8 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 44.3 dBmV
4 Locked ATDMA 1 5120 Ksym/sec 35600000 Hz 44.8 dBmV
5 Locked ATDMA 5 1280 Ksym/sec 39600000 Hz 45.3 dBmV
6 Not Locked N/A Unknown 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked N/A Unknown 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked N/A Unknown 0 Ksym/sec 0 Hz 0.0 dBmV
Downstream OFDM Channels
Channel Lock Status Modulation/Profile ID Channel ID Frequency Power SNR/MER Active Subcarrier
Number Range Unerrored
Codewords Correctable
Codewords Uncorrectable
Codewords
1 Locked 3 45 690000000 Hz 11.3 dBmV 41.8 dB 1108~2987 0 0 0
2 Not Locked 0 0 0 Hz 0.0 dBmV 0.0 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 0.0 dBmV
2 Not Locked 0 0 0 Hz 0.0 dBmV
Current System Time: Mon Jan 23 16:37:26 2023
System Up Time 03:03:19

And here is the information shown on the "Event Log" page:

Event Log
Clear Log Refresh
Time Priority Description
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 19 2023 17:18:16 Notice (6) CM-STATUS message sent. Event Type Code: 24
Jan 20 2023 05:01:44 Alert (2) CM Certificate Error
Jan 22 2023 04:45:12 Notice (6) DS profile config update. DS Chan ID: 45.
Jan 22 2023 04:49:45 Notice (6) CM-STATUS message sent. Event Type Code: 5
Jan 22 2023 05:01:31 Alert (2) CM Certificate Error
Jan 23 2023 04:06:53 Critical (3) No Ranging Response received - T3 time-out
Jan 23 2023 05:01:36 Alert (2) CM Certificate Error
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Time Not Established Warning (5) RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW
Jan 23 2023 12:09:04 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jan 23 2023 12:09:04 Notice (6) TLV-11 - unrecognized OID
Jan 23 2023 12:09:04 Critical (3) Config File Rejected due to Invalid or Unexpected TLV 11
Jan 23 2023 12:09:14 Warning (5) RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
Jan 23 2023 12:09:22 Alert (2) CM Certificate Error
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Time Not Established Warning (5) RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW
Jan 23 2023 12:29:10 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jan 23 2023 12:29:10 Notice (6) TLV-11 - unrecognized OID
Jan 23 2023 12:29:10 Critical (3) Config File Rejected due to Invalid or Unexpected TLV 11
Jan 23 2023 12:29:20 Warning (5) RCS Partial Service
Jan 23 2023 12:29:20 Warning (5) RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
Jan 23 2023 12:29:29 Alert (2) CM Certificate Error
Jan 23 2023 12:29:31 Notice (6) CM-STATUS message sent. Event Type Code: 4
Jan 23 2023 13:07:25 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jan 23 2023 13:07:25 Notice (6) TLV-11 - unrecognized OID
Jan 23 2023 13:07:25 Critical (3) Config File Rejected due to Invalid or Unexpected TLV 11
Jan 23 2023 13:07:31 Warning (5) RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
Jan 23 2023 13:07:40 Alert (2) CM Certificate Error
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Jan 23 2023 13:14:41 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jan 23 2023 13:14:41 Notice (6) TLV-11 - unrecognized OID
Jan 23 2023 13:14:41 Critical (3) Config File Rejected due to Invalid or Unexpected TLV 11
Jan 23 2023 13:14:46 Warning (5) RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
Jan 23 2023 13:14:53 Alert (2) CM Certificate Error
Time Not Established Critical (3) No Ranging Response received - T3 time-out
Jan 23 2023 13:35:48 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jan 23 2023 13:35:48 Notice (6) TLV-11 - unrecognized OID
Jan 23 2023 13:35:48 Critical (3) Config File Rejected due to Invalid or Unexpected TLV 11
Jan 23 2023 13:35:57 Warning (5) RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
Jan 23 2023 13:36:05 Alert (2) CM Certificate Error

Any help on this would be much appreciated.