Constant Disonnects

Question

I have been experincing constant disconnects which seem to be getting more frequent and annoying. I am using a Netgear CM500 which is fairly new but experinced the same disconnects with my previous motorola surfboard modem. FInally had a tech come out today who said he dialed down the frequency level a little as it was high and should be fine. Disocnnects are still occuring several hours after and more frequent. A few weeks ago i disconnected the splitter and runnig the line straight to the modem but same issue. Also about a year ago i had comcast run a new line after they determined the line was not good.

I noticed in the modems error log the following throughout the day:

No Ranging Response received - T3 time-out

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received

Unicast Ranging Received Abort Response - Re-initializing

These are the frequency stats on the modem. I appreciate any advice.

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	579000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	Enabled	BPI+
IP Provisioning Mode	Honor MDD	honorMdd(4)

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	25	579000000 Hz	11.7 dBmV	37 dB	7507	0
2	Locked	QAM256	26	585000000 Hz	11.4 dBmV	36.9 dB	8835	0
3	Locked	QAM256	27	591000000 Hz	11.4 dBmV	36.8 dB	9976	0
4	Locked	QAM256	28	597000000 Hz	11.3 dBmV	36.8 dB	10124	0
5	Locked	QAM256	29	603000000 Hz	11.2 dBmV	36.7 dB	11700	0
6	Locked	QAM256	30	609000000 Hz	11.2 dBmV	36.6 dB	10995	0
7	Locked	QAM256	31	615000000 Hz	10.9 dBmV	36.5 dB	14178	0
8	Locked	QAM256	32	621000000 Hz	11 dBmV	36.5 dB	14887	0
9	Locked	QAM256	33	627000000 Hz	10.9 dBmV	36.4 dB	15172	0
10	Locked	QAM256	34	633000000 Hz	10.7 dBmV	36.2 dB	18390	0
11	Locked	QAM256	35	639000000 Hz	10.7 dBmV	36.2 dB	19561	0
12	Locked	QAM256	36	645000000 Hz	10.6 dBmV	36.2 dB	20871	0
13	Locked	QAM256	37	651000000 Hz	10.7 dBmV	36.2 dB	19764	0
14	Locked	QAM256	38	657000000 Hz	10.7 dBmV	36.1 dB	21112	0
15	Locked	QAM256	39	663000000 Hz	10.7 dBmV	36.1 dB	22516	0
16	Locked	QAM256	40	669000000 Hz	10.8 dBmV	36.1 dB	22778	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	10	5120 Ksym/sec	29200000 Hz	50 dBmV
2	Locked	ATDMA	9	5120 Ksym/sec	35600000 Hz	50.5 dBmV
3	Locked	ATDMA	11	5120 Ksym/sec	22800000 Hz	50.5 dBmV
4	Locked	ATDMA	12	5120 Ksym/sec	16400000 Hz	49 dBmV

Extended Upstream Transmit Power

Enable Extended Upstream Transmit Power

Current System Time:Sat Oct 24 18:21:50 2020

System Up Time:00:31:23

riehs · Answer

The tech was just out here this morning and he said he actually lowered the levels beacause they were too high. Regarding the splitters, as i mentioned already i have removed already which does not seem to have made any difference.

EG · Answer

The upstream power is too high and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting 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 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test.

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 book a tech visit to investigate and correct.

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EG · Answer

If the tech visit was before you posted that upstream power level, then it wasn't enough..... it wasn't even enough for the downstream. You were conned.

riehs · Answer

i guess so. where do i want that range to be within to have more stability.

EG · Answer

40 to 45 dB is preferred. Here are the specs;

Specification Min Max

Downstream Power Level
Cable Modems	-10dBmV	+10dBmV
Gateways and EMTAs	-7dBmV	+7dBmV
Downstream Signal to Noise Ratio	35dB	-
Upstream Power Level	+35dBmV	+50dBmV
Upstream Signal to Noise Ratio	31dB	-
Upstream Receive Power	-2dBmV	+2dBmV

riehs · Answer

so the 40-45 db i imagine you are referring to the upstream? maybe the tech only adjusted the downstream as it seems closer to the 35 reccomended. are there any other values that look like they need to be adjusted?

EG · Answer

@riehs wrote:so the 40-45 db i imagine you are referring to the upstream? Yes. maybe the tech only adjusted the downstream as it seems closer to the 35 reccomended. That's not the power level for the downstream.. It's the SNR. They can't just adjust that. They need to do things to the line to get it as high as possible. are there any other values that look like they need to be adjusted? No.

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Constant Disonnects

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