50mb Connection keeps cutting out

[Niceaction]

Since I upgraded to 50mb a month ago, my internet connection has cut out about once every hour. I need to pull the power cable out of the modem and put it back in again to get it working. This gets really frustrating after a while!

So an engineer came out today and experienced the problem while he was here and said I need a new modem, so he replaced that and it happened again. At which point he said it must be my router, so he replaced that.

The problem didn't happen for 10 minutes so he left.

It's now happened 3 times in the last 20 minutes! ARRRRGGGHHHH

I had a similar problem a few years ago, and I remember the engineer going into the modem settings and immediately saying that one of the numbers didn't look right (I think he said it should be around 50, but it was nowhere near) he then said he needed to make some changes to the box outside. He did that, and I didn't have the problem again.

So my question is... Is there something I can look for in the modem settings that will immediately tell me if something is wrong with my connection to the exchange?

Thanks

[Ben B]

Hi there,

Log in to your modem settings at http://192.168.100.1, if it asks you for a username and password they are both root and post your upstream and downstream power levels and your rxmer levels :)

[Niceaction]

Upstream Power Level: US1 - 49.75. DS2,3 and 4 blank.
Downstream Power Level: -7.18 -7.33 -7.32 -7.27
RXmer: 35.60 35.97 36.17 36.61

[Sephiroth]

Upstream Power Level: US1 - 49.75. DS2,3 and 4 blank.
Downstream Power Level: -7.18 -7.33 -7.32 -7.27
RXmer: 35.60 35.97 36.17 36.61

Actually we need more than those items. The Modulation affects whether your RxMER is too low; there are codeword errors that tell their stopry.

There is also the event log which tells even more (if it is provided after/during you've done stuff rather than after a reboot which rells us very little).

[Niceaction]

Modulation 256QAM 256QAM 256QAM 256QAM

Here is a sample of the event log. It's massive already, so I have only pasted the last 1/3rd.

Sat Jun 12 16:24:48 2010 Sat Jun 12 16:24:48 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:24:59 2010 Sat Jun 12 16:24:59 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:24:59 2010 Sat Jun 12 16:24:59 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:25:11 2010 Sat Jun 12 16:25:11 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:25:11 2010 Sat Jun 12 16:25:11 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:27:26 2010 Sat Jun 12 16:27:54 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:27:56 2010 Sat Jun 12 16:27:56 2010 Critical (3) Ranging Request Retries exausted;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:27:56 2010 Sat Jun 12 16:27:56 2010 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:28:07 2010 Sat Jun 12 16:28:07 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:28:07 2010 Sat Jun 12 16:28:07 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 16:47:37 2010 Sat Jun 12 16:47:37 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;

[speedfreak]

You might want to edit out your mac address from the log ;)

[Niceaction]

Cheers!

---------- Post added at 18:23 ---------- Previous post was at 18:19 ----------

The up arrow and down arrow on my modem are not lit up either. Apparently, this is a problem.

[Sephiroth]

I' d have preferred the full stats. For example, the codeword errors tell an important story and a full event log is more informative than the very small selection, particularly because of the time stamps etc.

Anyway, it's clear that your downstream power is far too low. It should be in the range -3 to +6 dBmv. The effect is that your primary DS channel is losing sync.

Your RxMER (Signal/Noise ratio) is just about OK - I'd prefer to see it above 36 dB across the board.

The cause could be a dodgy modem; noise ingress locally; loose coax.

[Niceaction]

I had a Attenuator on my coax cable, so have removed that to see what happens. So far so good. Here are my downstream stats with it off.

Power Level
(dBmV) 9.80 9.67 9.70 9.92
RxMER
(dB) 37.36 37.36 37.94 38.26

[Sephiroth]

As I said, full stats & event log are best because we don't have the advantage of seeing what you see. Especially now that your DS power is too high.

We need to see if you have codeword errors in normal use.

Was there just 1 attenuator? My advice would be no more than a 10 dB forward path attenuator.

[Niceaction]

Here is everything that I can pull off my modem. The Attenuator was a 15db one, and its the only one I can see.

The internet connection wasn't lost overnight, which is a good sign.

Cable Modem Status
Item Status Comments
Acquired Downstream Channel 298.751221 MHz Primary Downstream Locked
Ranged Upstream Channel 46.201382 MHz Success
Provisioning State OK Operational
Ethernet Link Status Up 100 Mbps/Full duplex

Cable Modem Downstream

DS-1 DS-2 DS-3 DS-4
Frequency 298750000 306750000 314750000 322750000
Lock Status
(QAM Lock/FEC Sync/MPEG Lock) Y/Y/Y Y/Y/Y Y/Y/Y Y/Y/Y
Channel Id 41 42 43 44
Modulation 256QAM 256QAM 256QAM 256QAM
Symbol Rate
(Msym/sec) 6.952 6.952 6.952 6.952
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level
(dBmV) 9.30 9.10 9.23 9.45
RxMER
(dB) 37.36 37.36 37.94 38.26
Correctable
Codewords 493937 515176 513381 514063
Uncorrectable
Codewords 1454124 1475778 1413201 1434147


Cable Modem Upstream
US-1 US-2 US-3 US-4
Channel Type 1.0 N/A N/A N/A
Channel ID 6 N/A N/A N/A
Frequency
(Hz) 46200000 N/A N/A N/A
Ranging Status Success N/A N/A N/A
Modulation 16QAM N/A N/A N/A
Symbol Rate
(KSym/sec) 2560 N/A N/A N/A
Mini-Slot Size 2 N/A N/A N/A
Power Level
(dBmV) 48.25 N/A N/A N/A
T1 Timeouts 0
T2 Timeouts 0 0 0 0
T3 Timeouts 2 0 0 0
T4 Timeouts 0 0 0 0

Cable Modem Upstream Burst



US-1
Req
Init Maint
Per Maint
Short Data
Long Data
(1)

(3)

(4)

(5)

(6)

Modulation Type QPSK QPSK QPSK 16QAM 16QAM
Differential Encoding OFF OFF OFF OFF OFF
Preamble Length 64 128 128 144 160
Preamble Value Offset 140 6 6 216 216
FEC Error Correction (T) 0 5 5 5 10
FEC Codeword Information Bytes (k) 16 34 34 78 235
Maximum Burst Size 2 0 0 8 0
Guard Time Size 8 48 48 8 8
Last Codeword Length FIX FIX FIX SHORT SHORT
Scrambler on/off ON ON ON ON ON



US-2
Modulation Type
Differential Encoding
Preamble Length
Preamble Value Offset
FEC Error Correction (T)
FEC Codeword Information Bytes (k)
Maximum Burst Size
Guard Time Size
Last Codeword Length
Scrambler on/off



US-3
Modulation Type
Differential Encoding
Preamble Length
Preamble Value Offset
FEC Error Correction (T)
FEC Codeword Information Bytes (k)
Maximum Burst Size
Guard Time Size
Last Codeword Length
Scrambler on/off



US-4
Modulation Type
Differential Encoding
Preamble Length
Preamble Value Offset
FEC Error Correction (T)
FEC Codeword Information Bytes (k)
Maximum Burst Size
Guard Time Size
Last Codeword Length
Scrambler on/off


Cable Modem Operation Configuration
General Configuration
Network Access : Allowed
Maximum Number of CPEs : 1
Baseline Privacy : Enabled
DOCSIS Mode : DOCSIS 3.0
Config File : S970025db892fe049.cm
Primary Downstream Service Flow
SFID : 8685
Max Traffic Rate : 53000000 bps
Max Traffic Burst : 10000 bytes
Min Traffic Rate : 0 bps
Primary Upstream Service Flow
SFID : 8724
Max Traffic Rate : 1750000 bps
Max Traffic Burst : 3044 bytes
Min Traffic Rate : 0 bps
Max Concatenated Burst : 0 bytes
Scheduling Type : Best Effort

Cable Modem Event Log
First Time Last Time Priority Description
Sat Jun 12 20:17:32 2010 Sat Jun 12 20:17:58 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:18:28 2010 Sat Jun 12 20:18:28 2010 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:18:42 2010 Time Not Established Warning (5) ToD request sent - No Response received;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Time Not Established Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Time Not Established Warning (5) ToD request sent - No Response received;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Time Not Established Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:19:58 2010 Sat Jun 12 20:19:58 2010 Critical (3) TFTP file complete - but missing mandatory TLV;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:27:57 2010 Sat Jun 12 20:28:09 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:29:58 2010 Sat Jun 12 20:29:58 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:29:58 2010 Sat Jun 12 20:29:58 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:30:08 2010 Sat Jun 12 20:30:08 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:30:08 2010 Sat Jun 12 20:30:08 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:31:40 2010 Sat Jun 12 20:33:00 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:33:30 2010 Sat Jun 12 20:33:30 2010 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:33:42 2010 Sat Jun 12 20:33:42 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:33:42 2010 Sat Jun 12 20:33:42 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:33:52 2010 Sat Jun 12 20:33:52 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:33:52 2010 Sat Jun 12 20:33:52 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:34:03 2010 Sat Jun 12 20:34:03 2010 Warning (5) ToD request sent - No Response received;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:34:03 2010 Sat Jun 12 20:34:03 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:34:03 2010 Sat Jun 12 20:34:03 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:34:58 2010 Sat Jun 12 20:37:58 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:39:14 2010 Sat Jun 12 20:39:14 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:39:14 2010 Sat Jun 12 20:39:14 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:39:24 2010 Sat Jun 12 20:39:24 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:39:24 2010 Sat Jun 12 20:39:24 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:39:34 2010 Sat Jun 12 20:39:34 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:39:34 2010 Sat Jun 12 20:39:34 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:42:28 2010 Sat Jun 12 20:42:57 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:42:59 2010 Sat Jun 12 20:42:59 2010 Critical (3) Ranging Request Retries exausted;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:42:59 2010 Sat Jun 12 20:42:59 2010 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:43:10 2010 Sat Jun 12 20:43:10 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:43:10 2010 Sat Jun 12 20:43:10 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:43:20 2010 Sat Jun 12 20:43:20 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:43:20 2010 Sat Jun 12 20:43:20 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:43:30 2010 Sat Jun 12 20:43:30 2010 Critical (3) SYNC Timing Synchronization failure - Failed to receive MAC SYNC frame within time-out period;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 20:43:30 2010 Sat Jun 12 20:43:30 2010 Error (4) RCS Primary DS Failure;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;
Sat Jun 12 22:43:03 2010 Sat Jun 12 22:45:29 2010 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.0;

Thanks.

[Sephiroth]

Thanks for that.

I presume the stuff in the log between 20:18 and 20:43 is your kerfuffling about time and it's been stable since.

Correctable
Codewords 493937 515176 513381 514063
Uncorrectable
Codewords 1454124 1475778 1413201 1434147

The uncorrectable codewords are hopefully historic. If they don't rise, then that's hopefully a problem cured.

The correctable codewords might be growing because of the high DS power. I would still have that attenuated by 9 or 10 dB (not 15). There could be something wrong in your local link to the cabinet - I obviously don't have the diagnostic tools. But watching the codeords is now your best diagnostic.

[Niceaction]

Thanks very much.

I'll buy a 10db attenuator to see what happens.

[Sephiroth]

Forward path attenuator.

[Peter_]

Thanks very much.

I'll buy a 10db attenuator to see what happens.
Is the any reason as to why you have called the 50Mb Support Team on 0800 052 0431 as buying and fitting an attenuator will be in breach of the T&C's and a call is free.

Call tomorrow after 0800.

[Niceaction]

Because it took 3 weeks for them to come out this time, after they didn't turn up on the date we had agreed. Then for Saturday, I had requested for them to come out 8am - 12pm as I work in the afternoon, but when it got to 12:30 I phoned them and was told that it had now been booked from 4pm - 7pm.

So I had to use an emergency days holiday to stay in.

The guy who came round to fix it clearly had no idea what he was doing, as he just replaced the modem and the router, and didn't even go into the settings to understand the issue.

If you want to employ numptys both on the phones and on site, it's no wonder people take matters into their own hands.

[Peter_]

I have no idea why a engineer would take 3 weeks to come out as we have to give you the first available slot and agree the time with you.

But if you feel that we are numpties I will leave it to you to break the T&C's of your contract and possibly cause issues on your neighbours connections.

[jb66]

What did you want the technician to do? Magic a solution, if your upstream is fine and your downstream + snr is in spec he has checked all he can

[Niceaction]

What did you want the technician to do? Magic a solution, if your upstream is fine and your downstream + snr is in spec he has checked all he can

According to Sephiroth's post...

Anyway, it's clear that your downstream power is far too low. It should be in the range -3 to +6 dBmv. The effect is that your primary DS channel is losing sync.

Your RxMER (Signal/Noise ratio) is just about OK - I'd prefer to see it above 36 dB across the board.


I gathered from that, that everything is not fine. Also, the stats that I posted are easily available from looking at the modem, so the guy who came out should have seen them.

To the previous poster, the reason it took 3 weeks to come out, is you guys conveniently didn't turn up at all for my first appointment, so I had to book again. As I work 50 miles away from home, I have to book days off to accomodate you, which can't be booked at the drop of a hat.

Basically, I have had enough, and so i'm doing something about it myself.

[jb66]

Are you saying the tech never even looked at the power level? If so I apologise as this is very basic. If your power levels are 9db without attenuator then it will run better without it, you could have had your tap switched by another tech

[Niceaction]

Sorry, yes. The technician just swapped over the modem and router, and didn't go anywhere near the settings.

[jb66]

Whats your stats, he could have adjusted things outside, has it cut off again?