C7800 Modem - Slow connections and Many Not Locked Channels

[Andy_Royce]

Installed C7800 (Firmware V3.01.43) about three weeks ago to take advantage of Xfinity 1Gb service and reduce rental cost of Xfinity equipment.  Since C7800 has been installed internet speeds have been intermittent, inconsistent and slow at times.  Started watching downstream bonded channels going from locked to unlocked periodically sometimes very often and noted power levels were generally around -1.5 up to +3.0 and at times uncorrectables in the thousands.  Have had three Xfinity techs on site and finally got them to replace cables, cable ends, splitters, tighten all cable connection and replace the trasformer that supports a Xfinity 8 way splitter all of which helped to stableize power levels to =7.5-9.0 reduced uncorrectables to zero for now but did not help many of the downstream channels from going from locked to not locked and back again.   Tech verified power levels going into house at 13DbmV. Chart below is current status of the modem...lots of unlocked channels.  Xfinity tech said he was escalating issue to next tier to have them verify what is going on at head end.  I am not sure anything is wrong with the modem but after reading many other forum messages here I am not sure what to think as it appears I am not the only one to experience these issues.  Thoughts?

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

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<tabindex=-1>Startup Procedure</tabindex=-1>

Procedure	Status	Comment
Acquire Downstream Channel	615000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	ENABLED	BPI+
IP Provisioning Mode	Honor MDD	IPv6 only

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<tabindex=-1>Downstream Bonded Channels</tabindex=-1>

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectabables
1	Locked	QAM256	25	615000000 Hz	8.0 dBmV	39.9 dB	0	0
2	Locked	QAM256	1	459000000 Hz	9.5 dBmV	40.5 dB	0	0
3	Locked	QAM256	2	465000000 Hz	9.6 dBmV	40.2 dB	0	0
4	Locked	QAM256	3	471000000 Hz	9.1 dBmV	40.3 dB	0	0
5	Locked	QAM256	4	477000000 Hz	8.7 dBmV	40.0 dB	0	0
6	Locked	QAM256	5	483000000 Hz	8.8 dBmV	40.3 dB	0	0
7	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
8	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
9	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
10	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
11	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
12	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
13	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
14	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
15	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
16	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
17	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
18	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
19	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
20	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
21	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
22	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
23	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
24	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
25	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
26	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
27	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
28	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
29	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
30	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
31	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0
32	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0

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<tabindex=-1>Upstream Bonded Channels</tabindex=-1>

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	1	5120 Ksym/sec	30100000 Hz	36.0 dBmV
2	Locked	ATDMA	2	5120 Ksym/sec	36500000 Hz	36.0 dBmV
3	Locked	ATDMA	3	5120 Ksym/sec	17300000 Hz	35.5 dBmV
4	Locked	ATDMA	4	5120 Ksym/sec	23700000 Hz	35.5 dBmV
5	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0 dBmV
6	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0 dBmV

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<tabindex=-1>Downstream OFDM Channels</tabindex=-1>

Channel	Channel ID	Indicator	Subcarrier Zero Frequency	Active Subcarrier Number Range	Total Codewords	Uncorrectable Codewords
1	159	Non-Primary	629600000 Hz	1126 ~ 2969	205257028	0
2	0	Other	0 Hz	0 ~ 0	0	0

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<tabindex=-1>Upstream OFDMA Channels</tabindex=-1>

Channel	UpstreamIsMuted	Ranging Status	Subcarrier Zero Frequency	Active Subcarrier Number Range	Symbols Per Frame	Tx Power
1		Other	0 Hz	0 ~ 0	0	0 dBmV
2		Other	0 Hz	0 ~ 0	0	0 dBmV

[michaelkenward]

You might get better and quicker replies, and find other answers, over in the appropriate section for your device:

Cable Modems & Routers

No need to repost there, unless you want to – that will just clutter up the place with duplicated messages – but you might find advice related to your hardware.

I have asked the Netgear moderator to move your message.

[plemans]

Try getting xfinity to repartition the C7800. I've had them send the wrong partitioning file to my modem before and cause issues. 

[Andy_Royce]

Not sure what you mean by a "partitioning file...what is that?  I have not heard of that terminology before.

[antinode]

> Not sure what you mean by a "partitioning file [...]

   My guess: "partition" --> "provision".

[plemans]

@antinode you're right. Typing and not rereading again