Re: CAX80 poor cable connection status

multiZ · ‎2024-02-16

After getting my cable modem activated with Xfinity, I am getting a very poor signal.

I use my own router downstream, in front of the CAX80, and this router gets no signal from the cable modem.

Here is the cable diagnostics:

Cable Diagnostic

Status: Poor

Action:
[Downstream Power Level/Upstream 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: Good

Downstream Status: Poor

Downstream Power Level: Poor
Downstream power is poor (14.9dBmV). The recommended level is between -10dBmV to 10dBmV.

Downstream SNR: Good

Upstream Status: Poor

Upstream Power Level: Poor
Upstream power is poor (29.3dBmV). The recommended level is from 30 to 55dBmV.

Current time: Fri Feb 16 19:49:38 2024

Startup Procedure
Acquire Downstream Channel: 399 MHz Locked
Connectivity State: OK Operational
Boot State: OK Operational
Security: Enabled BPI+

Downstream Bonded Channels
Channel LockedStatus Modulation ChannelID Frequency Power SNR Correctables Uncorrectables
1 Locked 256 QAM 42 399000000 Hz 14.8 dBmV 41.2 dB 0 0
2 Locked 256 QAM 1 477000000 Hz 14.6 dBmV 40.8 dB 0 0
3 Locked 256 QAM 2 483000000 Hz 14.5 dBmV 40.8 dB 0 0
4 Locked 256 QAM 3 489000000 Hz 14.6 dBmV 40.8 dB 0 0
5 Locked 256 QAM 4 495000000 Hz 14.5 dBmV 40.8 dB 0 0
6 Locked 256 QAM 5 507000000 Hz 14.4 dBmV 40.7 dB 0 0
7 Locked 256 QAM 6 513000000 Hz 14.3 dBmV 40.6 dB 0 0
8 Locked 256 QAM 7 519000000 Hz 14.1 dBmV 40.5 dB 0 0
9 Locked 256 QAM 8 525000000 Hz 14.1 dBmV 40.5 dB 0 0
10 Locked 256 QAM 9 531000000 Hz 14.1 dBmV 40.4 dB 0 0
11 Locked 256 QAM 10 537000000 Hz 14 dBmV 40.4 dB 0 0
12 Locked 256 QAM 11 543000000 Hz 13.9 dBmV 40.3 dB 0 0
13 Locked 256 QAM 12 549000000 Hz 13.8 dBmV 40.2 dB 0 0
14 Locked 256 QAM 13 555000000 Hz 13.9 dBmV 40.2 dB 0 0
15 Locked 256 QAM 14 561000000 Hz 13.8 dBmV 40.2 dB 0 0
16 Locked 256 QAM 15 567000000 Hz 13.7 dBmV 40.1 dB 0 0
17 Locked 256 QAM 16 573000000 Hz 13.8 dBmV 40.1 dB 0 0
18 Locked 256 QAM 17 579000000 Hz 13.8 dBmV 40.1 dB 0 0
19 Locked 256 QAM 18 585000000 Hz 13.8 dBmV 40 dB 0 0
20 Locked 256 QAM 19 591000000 Hz 13.8 dBmV 40 dB 0 0
21 Locked 256 QAM 34 453000000 Hz 14.7 dBmV 40.9 dB 0 0
22 Locked 256 QAM 35 459000000 Hz 14.5 dBmV 40.8 dB 0 0
23 Locked 256 QAM 36 465000000 Hz 14.5 dBmV 40.8 dB 0 0
24 Locked 256 QAM 37 471000000 Hz 14.5 dBmV 40.8 dB 0 0
25 Locked 256 QAM 38 423000000 Hz 14.8 dBmV 41 dB 0 0
26 Locked 256 QAM 39 429000000 Hz 14.7 dBmV 41 dB 0 0
27 Locked 256 QAM 40 435000000 Hz 14.8 dBmV 41 dB 0 0
28 Locked 256 QAM 41 441000000 Hz 14.6 dBmV 41 dB 0 0
29 Locked 256 QAM 43 405000000 Hz 14.9 dBmV 41.2 dB 0 0
30 Locked 256 QAM 44 411000000 Hz 14.9 dBmV 41.2 dB 0 0
31 Locked 256 QAM 45 417000000 Hz 14.8 dBmV 41.2 dB 0 0
32 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0

Upstream Bonded Channels
Channel LockedStatus ChannelType ChannelID SymbolRate Frequency Power
1 Locked ATDMA 1 5120 Ksym/sec 35600000 Hz 29.3 dBmV
2 Locked ATDMA 2 5120 Ksym/sec 29200000 Hz 29.3 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 29.3 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 16400000 Hz 29.5 dBmV
5 Locked ATDMA 5 1280 Ksym/sec 39600000 Hz 33.0 dBmV
6 Not Locked Unknown 0 0 0 0.0
7 Not Locked Unknown 0 0 0 0.0
8 Not Locked Unknown 0 0 0 0.0

Downstream OFDM Channels
Channel LockedStatus ProfileID ChannelID Frequency Power SNR/MER ActiveSubcarrier Unerror Correctable Uncorrectable
1 Locked 0 ,1 ,2 ,3 33 722000000 Hz 13.58 dBmV 38.5 dB 1108 ~ 2987 7432804 7418060 0
2 Not Locked 0 0 0 Hz 0 dBmV 0 dB 0 ~ 4095 0 0 0

Upstream OFDMA Channels
Channel LockedStatus ProfileID ChannelID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV

Event Log
Time Priority Description
Fri Feb 16 19:09:01 2024 Warning Dynamic Range Window violation
Fri Feb 16 19:09:01 2024 Warning RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:01:5c:ae:c8:85;CM-QOS=1.1;CM-VER=3.1;
Fri Feb 16 19:08:56 2024 Critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:01:5c:ae:c8:85;CM-QOS=1.1;CM-VER=3.1;
Fri Feb 16 19:08:56 2024 Notice DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:01:5c:ae:c8:85;CM-QOS=1.1;CM-VER=3.1;
Fri Feb 16 19:08:25 2024 Notice TLV-11 - unrecognized OID;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:01:5c:ae:c8:85;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:00:50 1970 Notice Honoring MDD; IP provisioning mode = IPv6
Thu Jan 1 00:00:43 1970 Critical SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:00:49 1970 Critical No Ranging Response received - T3 time-out;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:01:5c:ae:c8:85;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:00:44 1970 Critical SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:00:48 1970 Critical No Ranging Response received - T3 time-out;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:01:5c:ae:c8:85;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:03:23 1970 Critical SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:02:59 1970 Critical SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Thu Jan 1 00:01:06 1970 Critical SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=94:18:65:cb:9b:db;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

The Xfinity app is useless. It has no option for poor signal quality, only gives instructions to reboot the modem.

What should my next steps be.

Does my model get its signal from the closet box (this is where the signal comes in for my ATT fiber connection)

Regards

multiZ

FURRYe38 · ‎2024-02-16

Power is TOO HIGH:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

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.

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box.
Be sure your using good quality RG6 coax cable up to the modem.
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.

multiZ · ‎2024-02-20

Thanks. I'll get in touch with Xfinity and see what they have to say.

I'll report back after I hear from them.

multiZ · ‎2024-02-20

I spoke to a Xfinity agent on a chat & it was a terrible experience.

I provided them with the cable data statistics, but they apparently ignored it.

They declared it a cable modem issue - said the the signal looked fine from their end and so it was not their problem.

The tech who started the service a year ago was much better - he checked the signal at the service box and my modem. Since i activated my new cax80, the signal looks terrible.

Both modems were CAX80 - how can the signal reception be so different?

Kitsap · ‎2024-02-20

Unless you get some help from Xfinity, sounds like you are on your own. The ideal power level runs between 0 and +1 dBmV. They make a Coax cable attenuator. Normally they come in 3, 6, and 10 db sizes. Here is a link to Amazon: https://a.co/d/1dDlyDd.

You really need to push on a different Xfinity button than chat. There are usually some more technically oriented responders over on the Reddit sub-forum for Comcast_Xfinity.

Here is a link: https://www.reddit.com/r/Comcast_Xfinity/wiki/knowledgebase/next-generation-internet/

Is there any chance you have an amplifier in your coax line?

Good luck!

Kitsap · ‎2024-02-20

Your CAX80 is a combination modem/router. It can be configured for modem only mode for use with a separate router downstream. When the CAX80 is in modem only mode, there is a good chance the only output port that is active is port 1.

multiZ · ‎2024-02-21

Thank you. I will contact them.

multiZ · ‎2024-02-21

On the new CAX80, I have not disabled the router. I have been testing it for good signal with my laptop.

Kitsap · ‎2024-02-21

@multiZ wrote:
On the new CAX80, I have not disabled the router. I have been testing it for good signal with my laptop.

When you say testing for good signal with my laptop, do you mean with a Wi-Fi connection to the laptop or via an Ethernet cable to the laptop?

When you do throughput testing on your laptop computer, recommend you use the Ookla stand alone application available in the play store. Please report actual numbers in Mbps, not just an assessment of good or bad.

Saw your post over on Reddit. Keep us appraised of your progress as we cannot see the Modmail communications. Be sure and do not post any personal information here like addresses, names, or account numbers.

multiZ · ‎2024-02-25

My connection to the CAX80 is always through ethernet cables.

I don't use WiFi and have it disabled on the cable modem.

The subreddit group has asked for Modmail, with my name and IP address.

I'll report back on how that goes.

Many thanks!

Kitsap · ‎2024-02-25

@multiZ wrote:
My connection to the CAX80 is always through ethernet cables.
I don't use WiFi and have it disabled on the cable modem.

The subreddit group has asked for Modmail, with my name and IP address.

I'll report back on how that goes.

Many thanks!

Please do.

Thanks.