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Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

Need Help!  Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

 

CM400...

 

ProcedureStatusComment
Acquire Downstream Channel585000000 HzLocked
Connectivity StateOkOperational
Boot State----
Configuration File----
SecurityEnabled

BPI+

 

About 3pm CA time Sunday, July 3rd, Lost Internet Connectivity.  Appears old SB modem, Lease from TWC, died.  Replace it with NetGear CM400.  Had TWC active CM400, all seemed fine.  This morning, July 4th, internet was very slow, DNS failed queries.

 

Looking at modem (CM400) downstream seemed fine.

 

Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUnCorrectables
1LockedQAM 2561543000000 Hz-8.4 dBmV36.1 dB10637
2LockedQAM 2562549000000 Hz-7.9 dBmV36.3 dB1592
3LockedQAM 2563555000000 Hz-7.7 dBmV36.8 dB0501
4LockedQAM 2564561000000 Hz-7.0 dBmV37.0 dB01485
5LockedQAM 2565567000000 Hz-6.5 dBmV37.6 dB14659
6LockedQAM 2566573000000 Hz-6.3 dBmV37.6 dB41638
7LockedQAM 2567579000000 Hz-6.3 dBmV37.9 dB72612
8LockedQAM 2568585000000 Hz-6.5 dBmV37.3 dB20647

 


Upstream seemed fine, if power level was a bit high at 51/52 per locked upstream channel, but this was normal compared to past, and as noted above, internet connecitivity has been solid over the last 6 years, barring a few minor outages (external to home).

 

However, over the couse of the last 16 hours, CM400 has losted Upstream channels, 1 at time, ever few hours.  Checked cables, checked splitters, etc. no unterminated connections, etc.  But right now, only have 1 Upstream channel and power level is 57!

 

Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA195120 Ksym/sec30600000 Hz57.0 dBmV
2Not LockedN/AUnknown0 Ksym/sec0 Hz57.0 dBmV
3Not LockedN/AUnknown0 Ksym/sec0 Hz57.0 dBmV
4Not LockedN/AUnknown0 Ksym/sec0 Hz

57.0 dBmV

 

 

Error log...

 

TimePriorityDescription
Time Not EstablishedCritical (3)No Ranging Response received - T3 time-out
Jul 5 03:31:34 2016Warning (5)MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jul 5 03:32:14 2016Critical (3)No Ranging Response received - T3 time-out
Jul 4 19:32:27 2016Warning (5)MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1

 

Error log is pretty clean given the capture above, but was getting a lot of T3 and T4 errors, lot of failure on upstream ranging errors, etc.

 

Figure I need to schedule a service call?

 

9 REPLIES 9
Expert

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

No, you need to get the extra splitters out of the line. Modem must be on no or the first 2 way if you have cable TV.

 This looks like several and with open ports. Your downstream is low and the upstream is maxed out and out of range

 

Rookie

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

After reboot this morning at about 5am (CA) time, was stable all day.  just before lost of connectivity, had a bunch of T3 and T4 errors.  After stable all day, this evening, bunch of T3 and T4 errors 8pm (CA) time.  And had to reboot the modem again.  All day had 3 upstreams locked, at 51/51 power level, but now after 8pm reboot of modem, back to 1 upstream at 57 power level!  This is the same pattern, with slightly different time frames over the last 3 days.

 

Since I can't find any more splitters, can't seem to get downstream power level up, and can't seem to get upstream power level down, I am at a loss.

 

Current configuration...

 

Acquire Downstream Channel633000000 HzLocked
Connectivity StateOkOperational
Boot State----
Configuration File----
SecurityEnabledBPI+

Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUnCorrectables
1LockedQAM 2567579000000 Hz-6.5 dBmV36.8 dB0511
2LockedQAM 2568585000000 Hz-6.7 dBmV36.8 dB0596
3LockedQAM 2569591000000 Hz-7.5 dBmV36.8 dB0504
4LockedQAM 25610597000000 Hz-8.0 dBmV37.6 dB48661
5LockedQAM 25611603000000 Hz-8.3 dBmV36.6 dB15683
6LockedQAM 25612609000000 Hz-8.3 dBmV36.6 dB15598
7LockedQAM 25613615000000 Hz-7.8 dBmV37.3 dB141467
8LockedQAM 25616633000000 Hz-6.7 dBmV37.3 dB44610

Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA195120 Ksym/sec30600000 Hz57.0 dBmV
2Not LockedN/AUnknown0 Ksym/sec0 Hz57.0 dBmV
3Not LockedN/AUnknown0 Ksym/sec0 Hz57.0 dBmV
4Not LockedN/AUnknown0 Ksym/sec0 Hz

57.0 dBmV

 

 

I have checked all cable terminations, all are connected or capped, with a proper termination cap (with center pin).  So I am at a loss what to try next.  I have an additional cable modem on order (different make and model) from the NetGear CM400, but I am not sure the CM400 is part of the issue here, I think the issue is in the wiring internal or external to the house.  TWC stated that work was done Sunday near my address, and it was then, after almost perfect connectivity for over 5 years, I get this current situation?  Kind of odd circumstance.

Rookie

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

Error log... Had to reboot modem again, after posting above...  and again the number of upstream channels that locked, changed again.

 

Jul 5 18:57:11 2016Warning (5)MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jul 5 19:06:24 2016Critical (3)No Ranging Response received - T3 time-out
Jul 5 19:08:29 2016Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
Jul 5 19:08:40 2016Critical (3)No Ranging Response received - T3 time-out
Jul 6 03:08:48 2016Warning (5)MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jul 6 03:08:58 2016Critical (3)No Ranging Response received - T3 time-out
Jul 5 19:09:14 2016Warning (5)MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Jul 5 19:10:14 2016Warning (5)Initializing Channel Timeout Expires - Time the CM can perform initial ranging on all upstream channels in the TCS has expired
Jul 5 19:10:14 2016Warning (5)TCS Partial Service
Jul 5 19:10:44 2016Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
Jul 5 19:12:30 2016Critical (3)No Ranging Response received - T3 time-out
Jul 5 19:12:44 2016Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

 

 

Note change in upstream channels that locked...  And power levels stepped back down again!  This makes no sense (at least to me) that the upstream power level would be so inconsistent.

 

ProcedureStatusComment
Acquire Downstream Channel597000000 HzLocked
Connectivity StateOkOperational
Boot State----
Configuration File----
SecurityEnabledBPI+

Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUnCorrectables
1LockedQAM 2561543000000 Hz-8.5 dBmV36.1 dB15624
2LockedQAM 2562549000000 Hz-8.1 dBmV36.3 dB1549
3LockedQAM 2563555000000 Hz-7.9 dBmV36.8 dB0543
4LockedQAM 2564561000000 Hz-7.1 dBmV36.8 dB0543
5LockedQAM 2566573000000 Hz-6.3 dBmV37.3 dB19699
6LockedQAM 2568585000000 Hz-6.4 dBmV37.3 dB21581
7LockedQAM 2569591000000 Hz-7.1 dBmV37.0 dB13675
8LockedQAM 25610597000000 Hz-7.8 dBmV37.0 dB14669

Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedTDMA172560 Ksym/sec18500000 Hz52.0 dBmV
2LockedATDMA185120 Ksym/sec23300000 Hz51.0 dBmV
3Not LockedN/AUnknown0 Ksym/sec0 Hz51.0 dBmV
4Not LockedN/AUnknown0 Ksym/sec0 Hz

51.0 dBmV

 

 

 

Expert

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

Get rid of ALL the splitters and call me in the morning. Woman LOLmodem MUST BE on the first 2 way or no splitter. dvr/cable boxes AFTER that first splitter

 

  Yours is not, especially if there's terminated ports...

 Your levels are near/ or out of spec US needs to be below +50 dBmv and upstream should be closer to 0 dBmv

 

Rookie

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

MsRaye,

 

 

I think in past discussion, a misunderstanding has resulted, there has never been more than one splitter on the cable modem run/line.  For over 6 years, was stable for the most part, except for the occasional T3 or T4 error, maybe 3 or 4 per year.

 

 

I have removed the single splitter as you suggested, and this improved the down stream powerlevels, they moved from 7-8 range to 2-3 range, so that is a significant improvement.  But the upstream powerlevels remain unchanged for the most part, still 51-52 range per locked channel.  Now, without the splitter I get 3 or 4 upstreams locked, where as with the splitter sometimes I got 1, most of the time 2 or 3 locked.

 

 


Acquire Downstream Channel 579000000 Hz Locked
Connectivity State Ok Operational
Boot State -- --
Configuration File -- --
Security Enabled BPI+
 
 

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables UnCorrectables
1 Locked QAM 256 6 573000000 Hz -2.5 dBmV 37.3 dB 1 513
2 Locked QAM 256 7 579000000 Hz -2.5 dBmV 37.9 dB 51 604
3 Locked QAM 256 8 585000000 Hz -2.6 dBmV 38.2 dB 0 598
4 Locked QAM 256 9 591000000 Hz -2.8 dBmV 37.9 dB 0 1401
5 Locked QAM 256 10 597000000 Hz -3.1 dBmV 37.9 dB 13 586
6 Locked QAM 256 11 603000000 Hz -3.3 dBmV 38.2 dB 16 589
7 Locked QAM 256 12 609000000 Hz -3.5 dBmV 38.2 dB 10 595
8 Locked QAM 256 15 627000000 Hz -2.5 dBmV 37.9 dB 18 586
 
 

Upstream Bonded Channels

Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked TDMA 17 2560 Ksym/sec 18500000 Hz 51.0 dBmV
2 Locked ATDMA 18 5120 Ksym/sec 23300000 Hz 51.0 dBmV
3 Locked ATDMA 19 5120 Ksym/sec 30600000 Hz 51.0 dBmV
4 Locked ATDMA 20 2560 Ksym/sec 37000000 Hz 51.0 dBmV

 
 

 


The odd thing is, now, since July 3rd, I am getting many T3 and T4 errors, from 4:30 to 5:30am (CA) and 7:30pm to 8pm (CA).  All day tends to be stable, all evening stable, except for the time frames noted above.

 

 

I have read other posts, that you have said, frequent T3 and T4 errors are an issue that is beyond what I can test, depending on where the issue is or what the issue is?  Today alone, for the last hour, 10s of T3 and sometimes T4 errors!  It took me over an hour just to get this reply posted given all the T3 resets.

 

 

Of course, I no longer have TV in the same room where I have the cable modem, and I also want that service, so what options do I have to get TV service?  Since the single splitter is obvious contributing to the instability of the connectivity now, if not before.

Expert

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

You're going to need twc out, something is wrong before the splitter, either in the outside box or out on the pole.

 All there  should be in the outside box is a grounding block... Is it corroded?

Can you see if there's splitters up on the pole?

 

Rookie

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

Yes, I will schedule a service call, I came the same conclusion, given the testing done.  With no splitter, the T3 and T4 events are hammering my modem, every morning and late evening.  Happened to day, from about 5:30am CA until 8pm (CA) was rock solid, then T3/T4 issues hit again, and now my powerlevels downstream jumped up, and I only have 1 upstream locked, get this... at 57!  Not good! 

 

The cable lines are underground trunk runs where I live.  Just about 6 years ago, when I first moved it, I had the run from my house to the demark replaced, and that might be the issue again.  The tech that came out swore that the line tested good, but he replaced it anyway, and all the issues disappeared. 

 

Maybe the same scenario again this time.  Thanks for the help and confirmation on testing.  I also have the option of moving to FiOS, I had FiOS in my previous residence, and it was wonderful, I think it was down once in 4 years, if I call right.

Expert

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

snap a couple pictures of the guts of the pedestal... probably corroded..

 

Rookie

Re: Need Help! Cable Modem (NetGear CM400) Started with 4 Upstreams Locked, Now Only One Locked

Well, the TWC tech just left and it was an interesting experience.  First, the tech was nice guy, he looked at the notes and data I had collected, which was a log of the cable modem errors, ping and trace-route reports, and record of power levels.

 

In summary here is what we, I say we, because I have worked in IT for over 30 years, and it is always nice when a tech shows up, and is open minded.  This is not always the case, I know from experience, hey TWC, the guy that did my service call, was smart and responsive, nice.

 

1) The tech replaced the older AMP at the block, and adjusted the wiring to ensure the cable modem got the best signal possible.  

 

2) He replaced the single splitter that was in place, with a TAP, ensuring the cable modem got the better leg.

 

3) The downstream levels changed over time randomly, from -4 to -6 at the low end and -8 to -10 at the upper end, not great but acceptable.  He got the downsteam levels to about -5 across all 8 downstream channels.

 

4) The upstream levels where not great, with 1 upstream locked, it was 57!  Not good.  WIth 2, 3 or sometimes 4 locked upstream channels the level per channel was 50/51 or 51/52, still not good.  After replace of the AMP and adjustment, the upstream channels were 38 to 43, with the first channel at 38, and last channel 43.

 

5) While the tech was onsight, he replaced the jumper leads, the short cables off the splitter to the cable modem, and the lead to the TV downstream AMP, yes I have a in-house downstream AMP to drive the 2 DTAs (TWC Digital Adapters) I have, this is needed due to the layout of the media room I have, he also checked the downstream AMP, and found it acceptable, given each leg off the downstream AMP is about -7, which fine for DTAs.

 

6) The tech found one of the short leads behind the splitter, the one to the in-house downstream AMP, had a bad connector, it was generating some signal errors, not significant, but the signal errors disappeared with the replacement of the bad connector. And since this issue was down the line from the splitter on the TV leg, the issue was not applicable to the cable modem.

 

Cable Block ------>TAP------>Cable Modem

                                |

                                `--------->In-House AMP----(replaced lead connector)----->DTA 1------>TV 1

                                                                 |

                                                                 `------------>DTA 2------>TV 2     

 

7) The tech did validate/test the cable run from the block (house side) to the demark (street consolidation point).

 

Demark-----(Good)---->House Block---(Good)---->(Replaced)TWC AMP---(Good)--->In-House----(Good)--->TAP, etc. (See diagram above)

 

So the upstream powerlevels were improved.  The minor issue on the DTA side legs was resolved, and the downstream in-house AMP, was ruled out as an issue.  But... the random and significant number of T3 errors continued.  While the tech was on sight, T3 errors reduced in volume, so the cable modem was not kicked offline, but about 30 minutes after the tech left, the massive T3 errors were back, and loss of connectivity via frequent cable modem reboots/resets resulted... again!  Not good.  Running the TWC speed check, was seeing some big up and down swings on the downward speed test, that was odd, that was new!

 

I called TWC support, worked my way past L1, L2, and got to L3 support... this is rare, as L3 support rarely is engaged via direct interaction with customers, but given the issue has been going on since the 3rd of the month, and today is the 17th.... lucky me.  L3 support suggested I swap the cable modem, which I suspected was the next step and I had a SB6141 I had purchased the week before (from Amazon, white variant), so I swapped out the NetGear CM400 with the SB6141. 

 

After about 10 minutes switching out the modems, the SB6141 was up and running.  And for the last 2 hours or so no T3 errors.  The downstream and upstream power levels continue to hold as noted above.  And if the connectivity is stable say for 24 or 48 hours, I will update this post accordingly.

 

The one odd issue is I am not sure TWC is sending the right modem profile down to the modem, since I can't login to the SB6141 via the login page, but I can access the configuration information via the direct URLs only... this is an issue other TWC users have had with SB6141, it is fixed when TWC pushes down the right profile.

 

Bottom line, it appears the NetGear CM400 is just not a good fit for my TWC environment, it is on the approved list, but in my case, it seems to either not handle well T3/T4 or prone to T3/T4 errors?  Whatever the case, improving the power levels alone was not sufficient.

 

Here is the firmware information:

 

Model Name: SB6141
Vendor Name: Motorola
Firmware Name: SB_KOMODO-1.0.6.14-SCM03-NOSH
Boot Version: PSPU-Boot(25CLK)(W) 1.0.12.18m5
Hardware Version: 8.0
Serial Number: [redacted]
Firmware Build Time: Jan 22 2015 14:31:03

 

Here the configuration information:

 

Frequency Plan:North American Standard/HRC/IRC
Custom Frequency Ordering:Default
Upstream Channel ID:18
Favorite Frequency (Hz)573000000
DOCSIS MIMOHonor MDD IP Mode
Modem's IP ModeIPv4 Only

 

Here is the error log during initial reboot, only one T3 error so far, normal for initial boot/setup:

 

Jul 18 2016 02:58:496-NoticeD106.0DHCP Renew - lease parameters time server-76.85.237.76;tftp file-?BEWGlysgPWYHQDAK1MNF@CtTDRTdrtsLIYWUmX+1EwNjMBIGwua15 modified;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jul 18 2016 02:58:494-ErrorD103.0DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jul 18 2016 02:30:476-NoticeI401.0TLV-11 - unrecognized OID;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jul 18 2016 02:30:475-WarningZ00.0MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:203-CriticalR02.0No Ranging Response received - T3 time-out;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:156-NoticeN/ACable Modem Reboot from SNMP ;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
Jul 18 2016 02:26:516-NoticeI401.0TLV-11 - unrecognized OID;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jul 18 2016 02:26:515-WarningZ00.0MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:01:5c:76:a8:60;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:156-NoticeN/ACable Modem Reboot due to power reset ;CM-MAC=20:3d:66:07:40:30;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

 

Here is the curent power level information:

 

Downstream Bonding Channel Value

Channel ID12 13 14 15 
Frequency573000000 Hz 579000000 Hz 585000000 Hz 591000000 Hz 609000000 Hz 615000000 Hz 621000000 Hz 627000000 Hz 
Signal to Noise Ratio37 dB 38 dB 38 dB 38 dB 38 dB 38 dB 38 dB 38 dB 
Downstream ModulationQAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 QAM256 
Power Level
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
-5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  -5 dBmV  

 

Upstream Bonding Channel Value
Channel ID18 17 19 20 
Frequency23300000 Hz 18500000 Hz 30600000 Hz 37000000 Hz 
Ranging Service ID9748 9748 9748 9748 
Symbol Rate5.120 Msym/sec 2.560 Msym/sec 5.120 Msym/sec 2.560 Msym/sec 
Power Level37 dBmV 35 dBmV 39 dBmV 40 dBmV 
Upstream Modulation[3] QPSK
[1] 16QAM
[2] 64QAM
 
[3] QPSK
[2] 16QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
[3] QPSK
[1] 16QAM
[2] 64QAM
 
Ranging StatusSuccess Success Success Success 

 

Signal Stats (Codewords)Bonding Channel Value
Channel ID12 13 14 15 
Total Unerrored Codewords129605530 129033180 129041367 129049641 129027035 129028909 129029990 129027987 
Total Correctable Codewords53 20 14 13 

Total Uncorrectable Codewords

522 1354 1494 1428 1459 662 658 646