13 Messages
Cable Modem Issues - T3 Timeout & Failed to acquire QAM/QPSK symbol timing, Uncorrectable Codeword Errors
I have xfinity gig extra plan. I have a Netgear Nighthawk CM3000 modem, which is brand new. I just replaced a relatively new CM2000 due to these issues, only to find the same thing happening with the new modem. The routers are TP link Decos, but they are fine.
I am having issues with intermittent connectivity, some random restarts, and web pages that don't load fully. There also seems to be some interference issues. I checked the modem logs and sure enough there are an enormous amount of uncorrectable codeword errors in my downstream OFDM channels only. They rack up at an alarming rate of almost one million per hour at times. I also have critical events for T3 timeouts, and SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing, whenever the modem is restarted.
I want to note that I took the modem down to where the coax line comes in from the street, and attached it there to test it before any splitters, other cables, etc. The power levels went up, but the issues persisted. Thus I suspect the issue is either outside the house, or possibly the single coax line that comes from the outside of my house (ISP entry point) to inside my house. Likely the former. I will post some diagnostic info below for reference. This was taken just minutes after rebooting. Again, despite power levels rising a bit, all of the issues remained the same when connecting the modem right to the first coax line. Same issues with two modems as well.
Does anyone know what the issue might be? Will I need a tech visit? If so, Xfinity please help!
Cable Diagnostic
Status: Good
Action:
Your setup looks fine. If you can't access the internet, make sure you properly activated the modem. If modem has been activated and you still can't access the internet, contact your service provider for troubleshooting help.
If you can access the internet but has other internet issue, the Netgear Cable Knowledge Base can provide additional troubleshooting info.
CM Status: Good
Downstream Status: Good
Downstream Power Level: Good
Downstream SNR Level: Good
Upstream Status: Good
Upstream Power Level: Good
Current Time: Mon Sep 16 18:36:32 2024
Startup Procedure
Acquire Downstream Channel: 513000000 Hz Locked
Connectivity State: OK Operational
Boot State: OK Operational
Security: Enabled BPI+
IP Provisioning Mode: Honor MDD IPv6 only
Downstream Bonded Channels
Channel LockedStatus Modulation ChannelID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 29 513000000 Hz -5.3 40.1 0 0
2 Locked QAM256 9 387000000 Hz -4.2 41 0 0
3 Locked QAM256 10 393000000 Hz -4.2 40.9 0 0
4 Locked QAM256 11 399000000 Hz -4.8 40.5 0 0
5 Locked QAM256 12 405000000 Hz -4.6 40.5 0 0
6 Locked QAM256 13 411000000 Hz -4.4 40.7 0 0
7 Locked QAM256 14 417000000 Hz -4.4 40.8 0 0
8 Locked QAM256 15 423000000 Hz -4.9 40.5 0 0
9 Locked QAM256 16 429000000 Hz -4.6 40.7 0 0
10 Locked QAM256 17 435000000 Hz -4.5 40.7 0 0
11 Locked QAM256 18 441000000 Hz -4.9 40.4 0 0
12 Locked QAM256 19 447000000 Hz -4.5 40.5 0 0
13 Locked QAM256 20 453000000 Hz -4.6 40.5 0 0
14 Locked QAM256 21 459000000 Hz -4.6 40.4 0 0
15 Locked QAM256 22 465000000 Hz -4.9 40.2 0 0
16 Locked QAM256 23 471000000 Hz -4.6 40.4 0 0
17 Locked QAM256 24 477000000 Hz -4.9 40.2 0 0
18 Locked QAM256 25 483000000 Hz -5.2 40 0 0
19 Locked QAM256 26 489000000 Hz -5.3 40 0 0
20 Locked QAM256 27 495000000 Hz -5.4 39.7 0 0
21 Locked QAM256 28 507000000 Hz -5.6 39.9 0 0
22 Locked QAM256 30 519000000 Hz -5.9 39.6 0 0
23 Locked QAM256 31 525000000 Hz -5.5 39.8 0 0
24 Locked QAM256 32 531000000 Hz -5.4 39.9 0 0
25 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0
26 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0
27 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0
28 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0
29 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0
30 Not Locked Unknown 0 0 Hz 0.0 0.0 0 0
31 Not Locked Unknown 0 0 Hz 0.0 0.0 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 47 5120 Ksym/sec 29200000 Hz 48.0 dBmV
2 Locked ATDMA 45 5120 Ksym/sec 16300000 Hz 48.8 dBmV
3 Locked ATDMA 46 5120 Ksym/sec 22800000 Hz 48.8 dBmV
4 Locked ATDMA 48 5120 Ksym/sec 35600000 Hz 47.0 dBmV
5 Not Locked Unknown 0 0 0 0.0
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 1 537000000 Hz -5.42 dBmV 37.7 dB 1108 ~ 2987 28760832 25848155 458143
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
Mon Sep 16 18:25:23 2024 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 1; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2.;
Mon Sep 16 18:23:25 2024 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 1; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.;
Mon Sep 16 18:21:20 2024 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 1; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;
Mon Sep 16 18:21:03 2024 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;
Mon Sep 16 18:20:59 2024 Notice (6) TLV-11 - unrecognized OID;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
Time Not Established Critical (3) No Ranging Response received - T3 time-out;
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;
thanks!
mikemot21
13 Messages
2 months ago
@Xfinity Support @XfinityRaul can anyone advise if I need a tech visit for these connection issues?
1
0
EG
Expert
•
106.9K Messages
2 months ago
Yes. That would be the next step. Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it up to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home. And if the problem is found to be on their side of the demarcation point, there will not be any charge.
Good luck !
0
mikemot21
13 Messages
2 months ago
Update. Tech came out and said it’s a bad line. Readings at their pole were good but readings at the end of line near my house were poor. They are putting a temporary line over my yard for now, and will then be sending people to lay one underground soon.
5
0