Modem Connection Drop

[Badcorgi]

Just upgraded to Xfinity Gig internet speed. Bought a CM1150V modem to accomodate 1gbps speed and replaced my Arris Surfboard. Install of CM1150V was long and difficult but Xfinity finally recognized it. 950 mbps speed was immediate and steady for about a week. Suddenly, internet speed dropped intermittently to ~1-2mbps while streaming Xfinity TV on my tablet at 3 a.m.  Then speed would suddenly blast back up to 950 mbps. Thought the problem was my 4 year old Nighthawk Router (R7000) so I bought a new Nighthawk (RAX50). Still have the problem. Mostly happens in the very early to mid morning hours for some strange reason. Xfinity says my connection is clear but plans to install a new underground cable line. Netgear tells me the problem is likely the number of locked and not locked channels in the upstream and downstream bonded channels. Xfinity has queried my modem and says it identified a timeout value for the boot file.  This is driving me crazy and will just ask Netgear to send me a replacement modem once the cable line is laid.  Anybody have similar experiences?  Thanks

[plemans]

do you have a screen snip of the cable connections page and logs? That actually helps check the line. 

[Badcorgi]

I do.  Please see below:

[plemans]

do you also have the cable connections page?

[Badcorgi]

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	591000000 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	20	591000000 Hz	3.3 dBmV	43.2 dB	0	0
2	Locked	QAM256	8	519000000 Hz	3.5 dBmV	43.5 dB	1	0
3	Locked	QAM256	9	525000000 Hz	3.4 dBmV	43.5 dB	1	0
4	Locked	QAM256	10	531000000 Hz	3.6 dBmV	43.6 dB	3	0
5	Locked	QAM256	11	537000000 Hz	3.6 dBmV	43.6 dB	1	0
6	Locked	QAM256	12	543000000 Hz	3.5 dBmV	43.5 dB	1	0
7	Locked	QAM256	13	549000000 Hz	3.4 dBmV	43.4 dB	1	0
8	Locked	QAM256	14	555000000 Hz	3.4 dBmV	43.4 dB	1	0
9	Locked	QAM256	15	561000000 Hz	3.4 dBmV	43.4 dB	0	0
10	Locked	QAM256	16	567000000 Hz	3.2 dBmV	43.3 dB	2	0
11	Locked	QAM256	17	573000000 Hz	3.2 dBmV	43.3 dB	1	0
12	Locked	QAM256	18	579000000 Hz	3.2 dBmV	43.3 dB	0	0
13	Locked	QAM256	19	585000000 Hz	3.3 dBmV	43.2 dB	1	0
14	Locked	QAM256	21	597000000 Hz	3.3 dBmV	43.1 dB	2	0
15	Locked	QAM256	22	603000000 Hz	3.5 dBmV	43.2 dB	0	0
16	Locked	QAM256	23	609000000 Hz	3.6 dBmV	43.2 dB	0	0
17	Locked	QAM256	24	615000000 Hz	3.5 dBmV	43.1 dB	0	0
18	Locked	QAM256	25	621000000 Hz	3.4 dBmV	42.9 dB	0	0
19	Locked	QAM256	26	627000000 Hz	3.3 dBmV	42.8 dB	0	0
20	Locked	QAM256	27	633000000 Hz	3.5 dBmV	42.9 dB	0	0
21	Locked	QAM256	28	639000000 Hz	3.5 dBmV	42.9 dB	1	0
22	Locked	QAM256	29	645000000 Hz	3.6 dBmV	43 dB	0	0
23	Locked	QAM256	30	651000000 Hz	3.7 dBmV	43.1 dB	0	0
24	Locked	QAM256	31	657000000 Hz	3.5 dBmV	42.9 dB	0	0
25	Locked	QAM256	32	663000000 Hz	3.5 dBmV	42.9 dB	0	0
26	Locked	QAM256	33	669000000 Hz	3.4 dBmV	42.8 dB	0	0
27	Locked	QAM256	34	675000000 Hz	3.2 dBmV	42.3 dB	0	0
28	Locked	QAM256	35	681000000 Hz	3.3 dBmV	42.8 dB	0	0
29	Locked	QAM256	36	687000000 Hz	3.5 dBmV	42.9 dB	0	0
30	Locked	QAM256	37	693000000 Hz	3.6 dBmV	43 dB	0	0
31	Locked	QAM256	38	699000000 Hz	3.5 dBmV	42.9 dB	0	0
32	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	1	5120 Ksym/sec	17300000 Hz	48 dBmV
2	Locked	ATDMA	2	5120 Ksym/sec	23700000 Hz	49.5 dBmV
3	Locked	ATDMA	3	5120 Ksym/sec	30300000 Hz	49.8 dBmV
4	Locked	ATDMA	4	5120 Ksym/sec	36700000 Hz	49.8 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

Downstream OFDM Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power	SNR / MER	Active Subcarrier Number Range	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	0 ,1 ,2 ,3	48	850000000 Hz	3.2 dBmV	41.9 dB	1108 ~ 2987	243544318	145272385	0
2	Not Locked	0	0	0 Hz	0 dBmV	0.0 dB	0 ~ 4095	0	0	0

Upstream OFDMA Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power
1	Not Locked	0	0	0 Hz	0 dBmV
2	Not Locked	0	0	0 Hz	0 dBmV

Current System Time:Wed Sep 23 13:27:32 2020System Up Time:05:52:41

[plemans]

your power/signal levels look pretty good. and most of your logs are from initial up. 

Are those levels while its having issues/after issues? 

If not, post the logs/signal levels after you have the issue

[Badcorgi]

Thank you Plemans for your assessment. I will do that when/if (fingers crossed) it happens again.

The problem usually happens in the very early morning hours (3 a.m.) and lasts until about 10 a.m.  This morning, I did a factory reset as well as a full reboot of the modem and the router.  From about 10:30 a.m. until this evening, I have been getting a glorious performance (950 mbps/40mbps).  When the new modem and new router are able to do their stuff, it is truly amazing! 

I am beginning to think it may be the cable node just outside my house.  The cable guy says the coaxial cable looks to be in good shape (it was installed only 2 years ago) and it is appropriate for gig speed.  The cable node however is likely the original from 1984 when the street was built.  A work order is in for installation of a new cable line and node box.  Cable guy says this will definitely improve things with consistent performance.  I will keep you up to date.

Thanks again! 🙂

[Badcorgi]

Update:  A new cable line was installed last Thursday and a technician was out here yet again to check the line and signal (3rd time).  All seems to be good and Xfinity had no other customers in the area with my problem and there have been no outages.  With my Arris Surfboard, I never experienced one issue with connectivity in 2 years.  I have come to the conclusion this is a faulty modem and will ask for a replacement.  This modem took about eight hours to finally connect with Xfinity when I installed it and I should have seen the writing on the wall then.  Still awaiting instructions back from Netgear and will reinstall my Arris while I await a new modem.

[Badcorgi]

Once again at 5 a.m., I tried to access the internet and found the usual "no internet connectivity" or abysmally slow speed (1mbps).  Frustrated, I reinstalled my Arris Surfboard and Nighthawk R7000.  NO issues whatsoever today.  Speed is slower (~500-600mbps) but I will take that. Internet access is consistent so I let Netgear know that it HAD to be a faulty modem.  After reviewing all of my logs, efforts to factory reset, reboot and have Xfinity come out 3 times to include laying a new cable line, I was issued a RMA# and will receive a replacement CM1150V.  At that point, I will also reinstall my new Nighthawk AX6 (AX5400). When the modem was working, I easily received 950mbps/50mbps. I will give an update when that happens. Fingers crossed.  Stay tuned.

[Badcorgi]

Ok, so my replacement modem was delivered today.  I set it up with the help of Xfinity over the phone.  Took a good 45 minutes and several reboots but it IS up and running.  Good speeds (940/45) and so far, consistent.  I just hope this holds.  It seems others have said theirs have crapped out weeks to months after the fact.  I really really hope that is not the case here.  My old surfboard maintained a consistently fast download speed prior to the arrival of this replacement modem.  I really want this one to work because it is a REALLY good modem when it works. 

[Badcorgi]

Update: Well, the old "Started Unicast Maintenance Ranging - No Response received - T3 time-out" log message is consistently displayed with this replacement modem.  Trying to stream Xfinity T.V. this morning on my tablet found several stream disruptions and "no connection to internet" messages.  I am convinced this modem is a fine piece of equipment when it works but the problem lies between Netgear and Xfinity compatibility.  Both companies really need to hammer out the bugs with this product, as I am hardly alone with my issue.  I will continue to use it even though I have mediocre, sporadic service. If it becomes unbearably inconsistent like my first CM1150 modem, I will just reinstall my old Arris Surfboard which has been reliable. This modem will just become an expensive paperweight in my home office with the hopes that one day, Xfinity and Netgear can produce a reliable interaction between their products and provide a firmware udate.  Netgear was eager to close their ticket, so I just told them to go ahead since I am done trying to figure this out for both companies.