Modem CM500: many channels not locked; slow connection (1-2mbps)

See below. Is it normal for many channels not locked? The Internet starts fast, but over one hour or so drops to crawl speed (1mpbs or less). A reboot of the modem often fixes the problem, but it wil...

Troubleshooting

vkdelta
Oct 13, 2017
you have a serious noise issue either in home wiring or ISP's line. that is why most your downstream channels are NOT locked. and whatever is locked have lot of uncorrectable errors.

what modem did you have before CM500? did it have same problem? or you are moving into a new house/apartment?

tcq

Aspirant

Oct 12, 2017

Cable Connection

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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	519000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	Enabled	BPI+
IP Provisioning Mode	Honor MDD	honorMdd(4)

Downstream Bonded Channels (Partial Service)

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	2	519000000 Hz	0.2 dBmV	40.3 dB	0	0
2	Locked	QAM256	4	531000000 Hz	-0.8 dBmV	39.9 dB	1	0
3	Locked	QAM256	6	543000000 Hz	-2.2 dBmV	39.6 dB	1	0
4	Not Locked	Unknown	7	549000000 Hz	0.0 dBmV	0.0 dB	0	0
5	Not Locked	Unknown	9	561000000 Hz	0.0 dBmV	0.0 dB	0	0
6	Locked	QAM256	12	579000000 Hz	-10.6 dBmV	33.9 dB	39	0
7	Not Locked	Unknown	13	585000000 Hz	0.0 dBmV	0.0 dB	0	0
8	Not Locked	Unknown	14	591000000 Hz	0.0 dBmV	0.0 dB	0	0
9	Not Locked	Unknown	17	609000000 Hz	0.0 dBmV	0.0 dB	0	0
10	Not Locked	Unknown	21	633000000 Hz	0.0 dBmV	0.0 dB	0	0
11	Not Locked	Unknown	22	639000000 Hz	0.0 dBmV	0.0 dB	0	0
12	Not Locked	Unknown	23	645000000 Hz	0.0 dBmV	0.0 dB	0	0
13	Locked	QAM256	24	651000000 Hz	-3.5 dBmV	29.9 dB	3410759	19271
14	Locked	QAM256	30	705000000 Hz	1 dBmV	39.9 dB	2	0
15	Locked	QAM256	31	717000000 Hz	1.7 dBmV	39.9 dB	1	0
16	Locked	QAM256	32	723000000 Hz	1.2 dBmV	39.7 dB	1	0

Upstream Bonded Channels (Partial Service)

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	73	5120 Ksym/sec	17300000 Hz	47.8 dBmV
2	Locked	ATDMA	74	5120 Ksym/sec	23700000 Hz	47.8 dBmV
3	Locked	ATDMA	75	5120 Ksym/sec	30300000 Hz	51 dBmV
4	Not Locked	Unknown	76	0 Ksym/sec	36700000 Hz	0.0 dBmV

Current System Time:Wed Oct 11 21:55:14 2017

Help Center

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vkdelta

NETGEAR Employee Retired

Oct 12, 2017

please dont copy paste. instead attach them as screenshots.

from the info you have provided (I could not see Uncorrectables in the power page), it looks like you have US noise issue on comcast and thats why you are seeing lot of T3 timeouts in the event log. But this will cause low performance in US and not in downlink.

please post screenshot of the power page and not copy-paste them in the reponse as it misses right most columns.

tcq
Aspirant
Oct 13, 2017
Thank you for the help and sorry for the inconvience of copy&paste.
- vkdelta
  NETGEAR Employee Retired
  Oct 13, 2017
  you have a serious noise issue either in home wiring or ISP's line. that is why most your downstream channels are NOT locked. and whatever is locked have lot of uncorrectable errors.
  
  what modem did you have before CM500? did it have same problem? or you are moving into a new house/apartment?
  - tcq
    Aspirant
    Oct 14, 2017
    Following your advice, we got technical to check cable outside the house. The problem was there indeed. This case is solved. Thank you!

Forum Discussion

Modem CM500: many channels not locked; slow connection (1-2mbps)