Constant Disconnects

Hi all,

Having constant disconnects at the modem with XFINITY. Here are my modem (Netgear CM1150V) stats.

Upstream channel has power that looks slightly higher than spec (59 vs 57), but all else seems within reason (downstream within -15 to +15, SNR > 33, all within ~3 of each other).

Walking the line, I have one extension adapter that looks fine from visual inspection but several spots where the cable goes near internal power lines, etc. In all the cable travels ~80 feet from front left corner of the house (where the street wire comes in) to the back right corner of the house (where the cable modem sits in my office).

Any obvious red flags? I have a tech coming out Monday.

Thanks,

Michael

Downstream Bonded

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	13	507000000 Hz	-10.5 dBmV	39.3 dB	3782	0
2	Locked	QAM256	14	513000000 Hz	-11.9 dBmV	38.6 dB	31207	15
3	Locked	QAM256	15	519000000 Hz	-11.9 dBmV	38.7 dB	18233	9
4	Locked	QAM256	16	525000000 Hz	-11.5 dBmV	38.9 dB	10569	0
5	Locked	QAM256	17	531000000 Hz	-10.3 dBmV	39.4 dB	3112	0
6	Locked	QAM256	18	537000000 Hz	-11.2 dBmV	38.9 dB	4130	0
7	Locked	QAM256	19	543000000 Hz	-11.4 dBmV	38.8 dB	8580	6
8	Locked	QAM256	20	549000000 Hz	-12.1 dBmV	38.5 dB	10145	1
9	Locked	QAM256	21	555000000 Hz	-10.8 dBmV	39.1 dB	2942	0
10	Locked	QAM256	22	561000000 Hz	-11 dBmV	38.9 dB	1878	0
11	Locked	QAM256	23	567000000 Hz	-11.2 dBmV	38.9 dB	10640	9
12	Locked	QAM256	24	573000000 Hz	-13.1 dBmV	37.8 dB	12826	3
13	Locked	QAM256	25	579000000 Hz	-11.7 dBmV	38.5 dB	5736	0
14	Locked	QAM256	26	585000000 Hz	-11.3 dBmV	38.7 dB	2411	0
15	Locked	QAM256	27	591000000 Hz	-10.1 dBmV	39.1 dB	1300	0
16	Locked	QAM256	28	597000000 Hz	-12.3 dBmV	38.1 dB	5336	0
17	Locked	QAM256	29	603000000 Hz	-12.3 dBmV	38.1 dB	9557	3
18	Locked	QAM256	30	609000000 Hz	-12.6 dBmV	37.9 dB	5187	0
19	Locked	QAM256	31	615000000 Hz	-10.8 dBmV	38.6 dB	885	0
20	Locked	QAM256	32	621000000 Hz	-12.5 dBmV	37.8 dB	2432	0
21	Locked	QAM256	33	627000000 Hz	-13.7 dBmV	37.3 dB	10264	0
22	Locked	QAM256	34	633000000 Hz	-14.3 dBmV	37 dB	9583	0
23	Locked	QAM256	35	639000000 Hz	-11.6 dBmV	38.3 dB	1753	0
24	Locked	QAM256	36	645000000 Hz	-10.6 dBmV	38.5 dB	792	0
25	Locked	QAM256	37	651000000 Hz	-11.6 dBmV	38.1 dB	2971	0
26	Locked	QAM256	38	657000000 Hz	-12.7 dBmV	37.8 dB	4779	0
27	Locked	QAM256	39	663000000 Hz	-12 dBmV	38.1 dB	2959	0
28	Locked	QAM256	40	669000000 Hz	-10.8 dBmV	38.6 dB	574	0
29	Locked	QAM256	41	675000000 Hz	-11.8 dBmV	37.5 dB	829	0
30	Locked	QAM256	42	681000000 Hz	-13.2 dBmV	37.4 dB	3116	0
31	Locked	QAM256	43	687000000 Hz	-12.9 dBmV	37.6 dB	3830	0
32	Locked	QAM256	44	693000000 Hz	-11.4 dBmV	38.2 dB	549	0

Upstream Bonded

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	5	5120 Ksym/sec	35600000 Hz	59 dBmV
2	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
3	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
4	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
5	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
6	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV

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Responses

Accepted Solution

U

user_677409

Visitor

•

5 Messages

3 years ago

Issue resolved with Tech visit.

The root cause was the barrel extension connecting the 50 and 25ft cables. Though it didn't look off to my (untrained) eyes, after the tech recut the ends of the wires and installed a new extension, it worked fine. That plus adjusting or removing the filters at the street box and adding a passive splitter (to tweak the last ~3.5 dBmV of power so that I'm now at ~0 downstream and ~42 upstream) has me locked on 4 channels.

Thanks for the guidance on what to look for. The tech said it was useful to have datapoints that aligned to his hypothesis.

0

EG

Expert

•

111.5K Messages

3 years ago

The downstream power levels are out of spec. And the upstream power level is far out of spec ! It's so bad that only one upstream is locked in. Should be 3 to 5 channels.

That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to let the tech investigate and correct.

Good luck with it !

(edited)

1

0

U

user_677409

Visitor

•

5 Messages

@EG Thank you for the advice. The upstream locking only 1 channel seems fairly new, as the light on the upstream is usually green (meaning 2+ channels locked on this modem), but it has been amber since this last outage started.

Past the street to house 2-way splitter, there's only 1 other extension adapter inside the house. It looks like a 50 and a 25 foot RG6/U were pieced together using that one extension. Eliminating it would most likely require getting a 100ft cable (with ~25 ft of slack) or custom rolling the cable from a spool (beyond my ability, for a tech to do). I'll take a look at the adapter when everyone's gone to bed and another internet outage won't cause a house panic.

Only 3 "right angles" in the line: once at the front right of the house, once to get around a garage wall feature, once vertically to bring it up through the floor into the office. Of the 3, only the small one around the garage wall feature could be described as an "angle", the other 2 are "curves". Otherwise a fairly straight shot. Not sure if any of those constitute a sharp bend. Otherwise the line seems fine.

The other thread I'm monitoring is that there's a fair amount of discussion on the NetGear CM1150V forum re: that modem, in particular, having Upstream locking issues (vs. XFINITY or other 3P modems). We'll see what the tech thinks. Thanks for the help.

3 years ago

0

EG

Expert

•

111.5K Messages

3 years ago

A right "angle" would indeed be a *sharp bend*. If so, it's not good.

Please circle back here after the tech visit with how things turn out.

0

EG

Expert

•

111.5K Messages

3 years ago

@user_677409

My pleasure ! Glad that it got squared away !

(edited)

0

U

user_677409

Visitor

•

5 Messages

3 years ago

In this post here I detailed issues we were having re: our line, which seemed to be fixed by replacing a barrel extension. At the time, all power was in the ideal range: downstream at ~0, upstream at ~42.

Within 8 hours we've had 2 more sustained outages, with our current stats still showing just-barely-acceptable downstream/upstream (off by ~10 from ideal in each case). We have a new XV7 router/modem on the way (giving up on my own modem) to try to eliminate one source of issues.

Any thoughts about how a setup could revert, so quickly, after a tech has just visited and gotten the system to an acceptable state?

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	37	651000000 Hz	-11.2 dBmV	38.1 dB	7132785	5998735
2	Locked	QAM256	13	507000000 Hz	-9.6 dBmV	39.6 dB	7171867	6049318
3	Locked	QAM256	14	513000000 Hz	-10 dBmV	39.4 dB	7492730	6544700
4	Locked	QAM256	15	519000000 Hz	-9.8 dBmV	39.5 dB	7738543	6935040
5	Locked	QAM256	16	525000000 Hz	-9.9 dBmV	39.4 dB	7353715	6141366
6	Locked	QAM256	17	531000000 Hz	-9.4 dBmV	39.5 dB	7397480	6327423
7	Locked	QAM256	18	537000000 Hz	-9.5 dBmV	39.3 dB	7448503	6341137
8	Locked	QAM256	19	543000000 Hz	-9.2 dBmV	39.4 dB	7800539	6783755
9	Locked	QAM256	20	549000000 Hz	-9.6 dBmV	39.2 dB	7446869	6341454
10	Locked	QAM256	21	555000000 Hz	-9.4 dBmV	39.3 dB	7390918	6245949
11	Locked	QAM256	22	561000000 Hz	-10 dBmV	39 dB	7808728	6686596
12	Locked	QAM256	23	567000000 Hz	-9.6 dBmV	39.2 dB	7900632	7149294
13	Locked	QAM256	24	573000000 Hz	-10.6 dBmV	38.7 dB	7213296	5918187
14	Locked	QAM256	25	579000000 Hz	-10.1 dBmV	38.9 dB	7391795	6279454
15	Locked	QAM256	26	585000000 Hz	-10.7 dBmV	38.6 dB	7327388	6138397
16	Locked	QAM256	27	591000000 Hz	-9.6 dBmV	39 dB	7407024	6267468
17	Locked	QAM256	28	597000000 Hz	-10.7 dBmV	38.5 dB	7288010	6092010
18	Locked	QAM256	29	603000000 Hz	-10.7 dBmV	38.5 dB	7203950	5929869
19	Locked	QAM256	30	609000000 Hz	-11.5 dBmV	38.1 dB	7534560	6341202
20	Locked	QAM256	31	615000000 Hz	-10.8 dBmV	38.3 dB	7308818	6133627
21	Locked	QAM256	32	621000000 Hz	-11.6 dBmV	37.7 dB	7170293	5855897
22	Locked	QAM256	33	627000000 Hz	-11.5 dBmV	37.8 dB	7226316	5931831
23	Locked	QAM256	34	633000000 Hz	-12.5 dBmV	37.4 dB	7205773	5925951
24	Locked	QAM256	35	639000000 Hz	-11.5 dBmV	38 dB	7321807	6103268
25	Locked	QAM256	36	645000000 Hz	-10.9 dBmV	38.1 dB	7273159	6024666
26	Locked	QAM256	38	657000000 Hz	-12 dBmV	37.7 dB	7365482	6144780
27	Locked	QAM256	39	663000000 Hz	-11.8 dBmV	37.8 dB	7051719	5530306
28	Locked	QAM256	40	669000000 Hz	-11.4 dBmV	38 dB	7261633	5940381
29	Locked	QAM256	41	675000000 Hz	-12 dBmV	37 dB	7333929	6105399
30	Locked	QAM256	42	681000000 Hz	-12 dBmV	37.6 dB	7431464	6192496
31	Locked	QAM256	43	687000000 Hz	-11.1 dBmV	38 dB	7186544	5771980
32	Locked	QAM256	44	693000000 Hz	-11.3 dBmV	37.9 dB	7412399	6128219

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	2	5120 Ksym/sec	16400000 Hz	51 dBmV
2	Locked	ATDMA	3	5120 Ksym/sec	22800000 Hz	52 dBmV
3	Locked	ATDMA	4	5120 Ksym/sec	29200000 Hz	52 dBmV
4	Locked	ATDMA	5	5120 Ksym/sec	35600000 Hz	52.5 dBmV
5	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
6	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV

Note: This comment was created from a merged conversation originally titled Continued outages, even after tech visit

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Constant Disconnects

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EG

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EG

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