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; |
|
Broomsweeper
Contributor
•
116 Messages
4 days ago
Make sure all your ethernet cables are CAT 5E or higher. CAT 5 will not do. I had similar issues and one cable was at fault.
1
0
EG
Expert
•
109.4K Messages
4 days ago
@edjames
Ethernet cable is not the problem as you have a very high download speed. The CM 2050V is not compatible. These are the only third-party / retail purchased devices that are currently compatible with their new "Next Gen" upload speeds;
As are their XB6, XB7, and XB8 rented gateway devices.
(edited)
3
0
EG
Expert
•
109.4K Messages
4 days ago
@edjames
This should be addressed as well.
The downstream power is too high / out of spec. It may be over-driving the front-end receiver circuit of the modem. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
Is there a drop amplifier on the coax cable line leading to the modem ? If so, try removing / bypassing it and see. If not, you can try installing a -6 dB forward path-only attenuator pad such as this one on the coax port on the rear of the modem to knock that power level down and see;
https://www.amazon.com/line-Signal-Forward-Attenuator-FPA6-54/dp/B07882H96R
For areas that have been upgraded to the new Next Gen (mid-split) upload speeds;
https://www.multicominc.com/product/multicom-mul-fpa85-forward-path-attenuator
These won't affect the upload power which is within specs.
(edited)
1
0
EG
Expert
•
109.4K Messages
3 days ago
@edjames
Don't forget to address the high downstream power. Even if it's not a problem right now, it's a problem waiting to happen. Good luck !
0
0
edjames
8 Messages
3 days ago
I tried 6 dB and 9 dB bidirectional attenuators. I powered off the modem each time before installing. Both did exactly as expected - reducing the incoming signal strength by the indicated attenuation level and causing the modem to increase the outgoing signal power by the indicated attenuation level. For either attenuator, incoming signal strength was reduced to an acceptable level while outgoing signal power remained in acceptable levels.
Correctable errors on the bonded DL channels have gone from ~10 to ~0. Still no uncorrectable errors. Uncorrectable codewords on the ODFM DL channels seems to be noticeably fewer. Listed SNR values are ~40 dB. No change in DL or UL speeds.
Still seeing this error in the log:
No T3 ranging error observed yet, but those seem to happen at set times throughout the day.
EDIT: The T3 ranging timeout error has appeared:
Now if Comcast would do something about the situation.
(edited)
1
0
XfinityRaf
Official Employee
•
804 Messages
2 days ago
Hi @edjames. I wanted to circle back here to confirm that your modem is not on the eligible devices list which is why you are not seeing the faster upload speeds. Your feedback has been provided to our management team. If you need assistance with anything else, please submit a new post.
1
0