12 Messages

Saturday, March 29th, 2025

Gigabit X2 advertised UL is 300 mbps, but only obtaining 40 mbps

I've been on the Gigabit X2 service for several months and have never experienced the rated upload speed of 300 mbps.  The best I see is 40 mbps.  I have tested from a computer etherneted to my router which is etherneted to my CM2050V modem.  The modem now has the v10.01.03 firmware which is capable of providing 300 mbps upload service.  I've had Comcast Support reprovision the modem twice after the FW upgrade, but no change in UL speed.  DL speeds are pretty good.  I see 1.7 gbps from the internet with the right server.  No obvious dropped connections to the internet.

Channel status and modem log are attached.  Downstream channel values look good except power level is a bit high.  Only a few correctables and no uncorrectables.  I'm not sure about upstream.  The upstream bonded channel power levels look to be in specification.  No info on correctables or uncorrectables.

The log, however, is full of critical events of two kinds:

- Started Unicast Maintenance Ranging - No Response received - T3 time-out

- SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1

And this warning shows up:

- ToD request sent - No Response received;;CM-QOS=1.1;CM-VER=3.1

The fact that UL speed tops out at 40 mbps seems to suggest there is a provisioning issue, but the significant number of critical events suggest that there could also be line issues.

Would appreciate any help from a Comcast employee who can effectively troubleshoot this.  Front line phone support has not been able to resolve it.

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 501000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD IPv6 only
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 20 501000000 Hz 11.3 dBmV 39.9 dB 6 0
2 Locked QAM256 1 387000000 Hz 10.5 dBmV 39.4 dB 19 0
3 Locked QAM256 2 393000000 Hz 10.5 dBmV 39.4 dB 9 0
4 Locked QAM256 3 399000000 Hz 10.5 dBmV 39.4 dB 8 0
5 Locked QAM256 4 405000000 Hz 10.7 dBmV 39.5 dB 6 0
6 Locked QAM256 5 411000000 Hz 10.6 dBmV 39.5 dB 6 0
7 Locked QAM256 6 417000000 Hz 10.6 dBmV 39.4 dB 7 0
8 Locked QAM256 7 423000000 Hz 10.7 dBmV 39.5 dB 4 0
9 Locked QAM256 8 429000000 Hz 10.9 dBmV 39.6 dB 5 0
10 Locked QAM256 9 435000000 Hz 11.1 dBmV 39.6 dB 10 0
11 Locked QAM256 10 441000000 Hz 11.1 dBmV 39.7 dB 6 0
12 Locked QAM256 11 447000000 Hz 11.2 dBmV 39.7 dB 8 0
13 Locked QAM256 12 453000000 Hz 11.2 dBmV 39.7 dB 5 0
14 Locked QAM256 13 459000000 Hz 11.2 dBmV 39.8 dB 10 0
15 Locked QAM256 14 465000000 Hz 11.3 dBmV 39.8 dB 9 0
16 Locked QAM256 15 471000000 Hz 11.5 dBmV 39.8 dB 6 0
17 Locked QAM256 16 477000000 Hz 11.7 dBmV 39.9 dB 5 0
18 Locked QAM256 17 483000000 Hz 11.4 dBmV 39.8 dB 7 0
19 Locked QAM256 18 489000000 Hz 11.2 dBmV 39.8 dB 7 0
20 Locked QAM256 19 495000000 Hz 11.2 dBmV 39.9 dB 4 0
21 Locked QAM256 21 507000000 Hz 11.1 dBmV 39.9 dB 4 0
22 Locked QAM256 22 513000000 Hz 11.0 dBmV 39.9 dB 5 0
23 Locked QAM256 23 519000000 Hz 10.9 dBmV 39.9 dB 1 0
24 Locked QAM256 24 525000000 Hz 10.9 dBmV 39.9 dB 1 0
25 Locked QAM256 25 531000000 Hz 10.9 dBmV 39.8 dB 2 0
26 Locked QAM256 26 537000000 Hz 10.9 dBmV 39.9 dB 4 0
27 Locked QAM256 27 543000000 Hz 10.9 dBmV 40.0 dB 6 0
28 Locked QAM256 28 549000000 Hz 11.0 dBmV 39.9 dB 9 0
29 Locked QAM256 29 555000000 Hz 11.1 dBmV 40.0 dB 2 0
30 Locked QAM256 30 561000000 Hz 11.1 dBmV 40.0 dB 4 0
31 Locked QAM256 31 567000000 Hz 11.0 dBmV 39.9 dB 8 0
32 Locked QAM256 32 573000000 Hz 10.8 dBmV 39.8 dB 5 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 2 5120 Ksym/sec 22800000 Hz 40.0 dBmV
2 Locked ATDMA 1 5120 Ksym/sec 16400000 Hz 39.8 dBmV
3 Locked ATDMA 3 5120 Ksym/sec 29200000 Hz 40.0 dBmV
4 Locked ATDMA 4 5120 Ksym/sec 35600000 Hz 40.3 dBmV
5 Not Locked Unknown 0 0 0 0.0 dBmV
6 Not Locked Unknown 0 0 0 0.0 dBmV
7 Not Locked Unknown 0 0 0 0.0 dBmV
8 Not Locked Unknown 0 0 0 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock Status Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 193 722000000 Hz 12.48 dBmV 40.8 dB 448 ~ 3647 787846530 721957804 74749
2 Locked 0 ,1 ,2 ,3 194 957000000 Hz 14.58 dBmV 41.6 dB 148 ~ 3947 807001162 728225032 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Locked 12 ,13 41 36200000 Hz 32.0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV
 

Time Priority Description
Sat Mar 29 07:06:41 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 19:00:25 2025 (Notice (6)) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 19:00:19 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 13:32:19 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 13:22:49 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:26:00 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:25:59 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:25:53 2025 (Notice (6)) TLV-11 - unrecognized OID;;CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Notice (6)) Honoring MDD; IP provisioning mode = IPv6
Time Not Established (Critical (3)) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:19:32 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:19:30 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:19:24 2025 (Notice (6)) TLV-11 - unrecognized OID;;CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Notice (6)) Honoring MDD; IP provisioning mode = IPv6
Time Not Established (Critical (3)) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 12:18:05 2025 (Warning (5)) ToD request sent - No Response received;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 07:07:07 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 05:40:52 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 05:40:51 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 05:40:45 2025 (Notice (6)) TLV-11 - unrecognized OID;;CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Notice (6)) Honoring MDD; IP provisioning mode = IPv6
Time Not Established (Critical (3)) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 05:32:34 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 10 13.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 04:55:24 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 01:02:34 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 00:52:19 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;;CM-QOS=1.1;CM-VER=3.1;
Fri Mar 28 00:21:21 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 13:43:49 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 10 13; New Profile: 12 13.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 13:37:34 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 10 13.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 13:37:04 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 13:29:25 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 09:03:04 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 11 13; New Profile: 12 13.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 08:54:04 2025 (Notice (6)) US profile assignment change. US Chan ID: 41; Previous Profile: 12 13; New Profile: 11 13.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 08:30:46 2025 (Critical (3)) Started Unicast Maintenance Ranging - No Response received - T3 time-out;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 07:07:35 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 33; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 07:07:34 2025 (Notice (6)) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 07:07:28 2025 (Notice (6)) TLV-11 - unrecognized OID;;CM-QOS=1.1;CM-VER=3.1;
Time Not Established (Notice (6)) Honoring MDD; IP provisioning mode = IPv6
Time Not Established (Critical (3)) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Thu Mar 27 07:06:11 2025 (Warning (5)) ToD request sent - No Response received;;CM-QOS=1.1;CM-VER=3.1;
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