Basic Internet Connectivity And Modem Help

[robb5001]

I have had this error for the past 3-4 months now and have had 4 technicians come out in the past few weeks unable to solve this problem, my lines have no noise and all the wiring from the outside of the house to the modem have been replaced with RJ-6. I ran the line directly to the modem without the splitter and still have issues. The last tech that came out said he was going to have to drill holes in every wall that has a TV and run individual lines to each one even though I spent the entire day replacing the all the lines in the attic and still have the same issue, I really dont know what else to do then to just post this and hope for a fix.

Downstream   Freq/Power: 537.000 MHz 1 dBmV     Signal to Noise Ratio:  39 dB     Modulation: QAM256  

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Upstream   Freq/Power: 30.600 MHz 32 dBmV     Channel Type: DOCSIS 2.0 (ATDMA)     Symbol Rate: 5120 kSym/sec     Modulation: QAM64

[EG]

What exact issue are you having or are you just looking at the error log ? The upstream power is a bit low for a 64QAM transmit carrier. It should be in the 40 to 50dB range. The CMTS (Cable Modem Termination System) at your local headend facility may be having a hard time hearing your modem at that low of a power level. It may be a hardware problem with the modem itself. Are you renting the modem from them ? If so, has tech tried swapping it out ?

[robb5001]

I am currently renting the modem and have asked for a replacement but the techs say its not the problem, and the issue im having is the internet will drop and the modem will reset and I get that error in the event log.

Odd thing is when I take out the splitters and run a direct connection to the line the upstream drops to 28 DBmV

[EG · Accepted solution]

That's way too low. If the CMTS can't hear your modem reliably it will cause the modem to re-boot spontaneously in an attempt at re-ranging to try to establish a better connection.The techs should recognize this and either try replacing the modem, add padding somewhere, and/or have your line properly balanced. If it is not the modem then this sounds like a mis-adjusted upstream amp issue in the physical hardware on the poles to which those premise techs would have to escalate the issue to the line maintenance dept/techs for correction.

[robb5001]

Thanks, I have forwarded this thread to comcast support and hopefully they can get this figured out. I have spend so much time and money trying to fix this, if this works comcast should really look into how they train their techs.

[robb5001]

I was able to increase the upstream power a bit by adding a splitter at the main line into the house.

Downstream
	Freq/Power:	555.000 MHz	-7 dBmV
	Signal to Noise Ratio:	38 dB
	Modulation:	QAM256
Upstream
	Freq/Power:	30.600 MHz	38 dBmV
	Channel Type:	DOCSIS 2.0 (ATDMA)
	Symbol Rate:	5120 kSym/sec
	Modulation:	QAM64

[EG]

Adding a pad at that point may not accomplish anything other than making the upstream power level figure look prettier. Are you still having the issue ? Be careful with trying to balance the line yourself because it affects the downstream power as well. It is still o/k if it is remaining stable but if you weaken it too much you will still have connectivity issues. Most times things are better left to the pros.

[robb5001]

Tweaked it some more and im going to run this for a few days and see if I have any problems, if I do I can just revert it back to what it was and have yet another "pro" tech come out.

Downstream
	Freq/Power:	555.000 MHz	-8 dBmV
	Signal to Noise Ratio:	38 dB
	Modulation:	QAM256
Upstream
	Freq/Power:	30.600 MHz	39 dBmV
	Channel Type:	DOCSIS 2.0 (ATDMA)
	Symbol Rate:	5120 kSym/sec
	Modulation:	QAM64

[EG]

Good luck with it ! And if you please, can you post back with a follow up as I am curious. Thanks.

[robb5001]

I had to switch out a tap that goes to a tv and the modem for a splitter because my tv was not getting enough signal and now my modem downstream is near the breaking point but ill see how it does for a few days and post back with the results.

Downstream
	Freq/Power:	555.000 MHz	-10 dBmV
	Signal to Noise Ratio:	36 dB
	Modulation:	QAM256
Upstream
	Freq/Power:	30.600 MHz	41 dBmV
	Channel Type:	DOCSIS 2.0 (ATDMA)
	Symbol Rate:	5120 kSym/sec
	Modulation:	QAM64

[robb5001]

Can downstream power cause "No Ranging Response received - T3 time-out"?

got one 10 min after the most recent configuration.

[EG]

A small amount of T3's are not fatal errors and are normal and to be expected. I'm concerned as to whether or not the modem actually re-boots spontaneously anymore.

[robb5001]

Last night I had over 10 T3 errors and this caused the modem to reboot each time, this seems to happen more at night then during the day, also the downstream power went from -10 to -7 during the night and is slowly going back to -10 right now.

[EG]

Guess it's back to plan "B" then huh....

[robb5001]

Well I had another tech come out about a week ago, said everything looks good and that he was unable to find the problem. I did record the times it happens though: 7:37, 8:07, 8:37, 9:37, 10:57, 8:17, 8:27... the list goes on. I think I'm just going to switch to a different ISP, this it just completely unacceptable.

[andyross]

Those times look suspicious being in such a pattern.

[EG]

What could it be Doc ??

[Bartleby]

andyross,

Not sure what "pattern" you see.  Other than that the times indicated all end in seven.

Too bad the latest tech didn't find anything, but we don't know just how diligently they reviewed the "tweaks" robb5001 tried (assuming he still had them in place).

Sorry to hear that Comcast can't seem to work this out.  And EG certainly has given his usual good guidance.  Including the possibility of problems at the pole or line-related--and the potential need for this to be escalated.

@robb5001,  How far "upstream" did the latest tech take his checking?

[robb5001]

Last tech first checked the main "hub" outside my house thats near the street and then worked his way back all the way to modem and added a pad on the main line that goes into the house, this did help somewhat and instead of 10 times a night its around 3-5 times a night. The time the connection drops will end in a 7 about 95% of the time.

Downstream
	Freq/Power:	537.000 MHz	-6 dBmV
	Signal to Noise Ratio:	38 dB
	Modulation:	QAM256
Upstream
	Freq/Power:	30.600 MHz	39 dBmV
	Channel Type:	DOCSIS 2.0 (ATDMA)
	Symbol Rate:	5120 kSym/sec
	Modulation:	QAM64

[robb5001]

WHAT DO I HAVE TO DO TO FIX THIS

Every time I talk to tech support I just get "your connection looks fine", THATS BECAUSE ITS RANDOM.

I have had multiple tech's come out and all of them dont know what the problem is and tell me everything looks good, maybe its NOT my house and its Comcast's problem.

[bozobuttz]

rob, do you have any log messages related to "DCC" along with your T3 timeout messages?  If so, I'm having the exact same problem.  One day it happened to me every 10 minutes for several hours.  Basically, the CMTS tells the modem to change to a different channel which it cannot talk on for whatever reason, which then the modem has to reset itself in order to go back to the original channel.  So, the modem keeps getting bounced back and forth.

Also, what model of modem do you have?

[robb5001]

I have recently started getting DCC errors along with the T3 Timeout starting on the 10th, the day after the tech came out and added a pad to the line, my modem is a Arris TM502G

3/10/2011 12:08	20000200	3	No Ranging Response received - T3 time-out
3/10/2011 12:08	18000200	3	UCD invalid or channel unusable
3/10/2011 12:08	14020600	3	DCC aborted unable to communicate on new upstream channel
3/13/2011 22:33	20000200	3	No Ranging Response received - T3 time-out
3/13/2011 22:33	18000200	3	UCD invalid or channel unusable
3/13/2011 22:33	14020600	3	DCC aborted unable to communicate on new upstream channel
3/20/2011 11:33	20000200	3	No Ranging Response received - T3 time-out
3/20/2011 11:33	18000200	3	UCD invalid or channel unusable
3/20/2011 11:33	14020600	3	DCC aborted unable to communicate on new upstream channel
3/21/2011 15:47	20000200	3	No Ranging Response received - T3 time-out
3/21/2011 15:48	18000200	3	UCD invalid or channel unusable
3/21/2011 15:48	14020600	3	DCC aborted unable to communicate on new upstream channel
3/21/2011 23:22	20000200	3	No Ranging Response received - T3 time-out

[bozobuttz]

I'd say have them replace the modem with a newer D3.0 capable device.  That's what you're paying a rental fee for right?  I have a hunch that might solve your problem... it did for me... so far.

[robb5001]

I keep asking them to replace it but they wont, I dont think its the problem because the connection problems happen every night and all day on the weekends but not during the day on weekdays.

[robb5001]

I was able to get a replacement mta sent out due to no problems being found on the last visit, a tech will be here friday to replace it.

[robb5001]

I got a Arris TM722 and have no connection problems so far and during the weekend is the worst, I think the problem is finally fixed!!!

Just one other question, on the status page I see "MTA-PassWithWarnings" and then I look at the log and see "65517 ConfigFile - BadParam" would this cause any problems?

[Bartleby]

If the connection is working, don't obsess over the log.  Without the complete details, you might be chasing ghosts.

[JamesR]

I think someone, probably EG,, said it takes 19 consecutive T3s to initiate a Reboot.

Don't know that to be true, but I do know that if I go into my modem I se a lot of stuff in the logs and I am having no discernible problem that Time Fraime.

[Bartleby]

EG and the other connection experts have a knack for being right, around here.

Most folks that follow their logs and surf the web for what they see will only be further confused.

There is no magic number for T3s to reboot.  But signal issues tend to continue, unless resolved...and that's sometimes a tall order--and requires line work that I'm seeing no evidence has really happened.

New in-home hardware rarely works. long term, in the face of underlying issues.  If I've been paying any attention, at all.

[EG]

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JamesR wrote:

I think someone, probably EG,, said it takes 19 consecutive T3s to initiate a Reboot.

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16

[JamesR]

Oh yes, I meant sixteen.  Just a typo there

[outtolunc]

You aren't the only one.. I even replaced the modem as i wanted to stop paying $5/mo for something that was paid for a few years ago.

For the past few months the issue has been getting worse. 

For me, we will see dropped packets then a reset, the fun part is when it resets the date teleports back to 1970 on the logs.  An example would be being ssh'd into an remote server watching a thread that has a constant output, the stream will just stop (not drop), tick tock tick tock.. .. .. .. sometime (10-20 seconds) later, the stream continues. 

This is repeatable, multiple modems, over time, i even removed all excess cable between wall (primary feed point) and cable modem (meaning it lives behind the entertainment system now).  

I do have an internet router, that i have to swapped out with various models/firmware (firewall, no firewall), and i still get these errors in my modem logs.

Both cable modems are Motorola 5101's 

Old one had higher powers levels on it (sorry didn't record at the time).

Current values

************************

Downstream      Value

Frequency       723000000 Hz

Signal To Noise Ratio   37.8 dB

Power Level     4.6 dBmV

The Downstream Power Level reading is a snapshot taken at the time this pagewas requested. Please Reload/Refresh this Page for a new reading

Upstream        Value

Channel ID      10

Frequency       30600000 Hz

Power   48.9 dBmV

http://dynx.net/COMCAST 

Old modem logs

http://dynx.net/COMCAST/Modem%20Configuration%20%20Status%20-%20Event%20Log.htm

http://dynx.net/COMCAST/Modem%20Configuration%20%20Status%20-%20Event%20Log2.htm

New modem logs

http://dynx.net/COMCAST/Modem%20Configuration%20%20Status%20-%20Event%20Log3.htm

http://dynx.net/COMCAST/Modem%20Configuration%20%20Status%20-%20Event%20Log4.htm

http://dynx.net/COMCAST/Modem%20Configuration%20%20Status%20-%20Event%20Log5.htm

Just in the time since this post..

top of Log4

2011-03-28 19:15:18 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out

2011-03-28 18:27:44 6-Notice M571.1 Ethernet link up - ready to pass packets

2011-03-28 18:27:14 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out

2011-03-28 18:27:08 6-Notice M571.4 Ethernet link dormant - not currently active

top of Log5 (when posted to site)

2011-03-28 19:52:24 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out

2011-03-28 19:50:35 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing

2011-03-28 19:50:17 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out

2011-03-28 18:27:44 6-Notice M571.1 Ethernet link up - ready to pass packets

2011-03-28 18:27:14 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out

Interesting how it *lost* an entry in the logs ..hmm

And yes, after 16 (not counted) times, the modem will reset and faint screams can be heard echoing through the area.

[pepar]

I thought I'd bump this thread with a big "me too!"  Reading over these posts is like they walked in my shoes.  I have had problems for what seems like years ... OK, it actually has been years.

"No Ranging Response received - T3 time-out" and "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out" alternating, and all errors are tagged Jan 1, 1970.

Mty downstream is consistently -6dBmV to -7dBmV and upstream 50dBmV to 57dBmV.

Over the last two years ,,, I wasn't kidding ... Comcast tech have come to the house and gone over every connection from the pole to my cable modem (Surfboard DOCSIS 3.0) and redid the lot of them.  Early on, they even ran another underground coax from the pole to the house.  This is my fourth cable modem, the second DOCSIS Surfboard.  I have even changed routers ... I do not use the CM's router.

I *just* got off the phone with Comcast tech support and left it with them that I'd try another cable modem.  I can't believe that is it, but I am at wit's end here.

Is there a modem other than the Motorola Surfboard that I should try?

Jeff

[EG]

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pepar wrote:

and upstream 50dBmV to 57dBmv

---

Ding ding ding. That is a problem. The transmit power should never fluctuate more than a max of 3dB. Seems that there is an RF connection quality issue with your line and is likely that it would still exist even with a different modem.

[pepar]

The Comcast tech was there yesterday, but before he came I had spoken to Motorola tech support and was told that the modem could go to 58dBmV, but would begin to distort (right word?) over 50.  They had told me about splitters and such, too.  I looked over my installation and saw that the leg from the initial 3-way that went to the cable modem had a very sharp bend in it.  I undid some things to remove much of that and immediately saw my upstream drop to 48dBmV.

The tech did some more along those lines and chopped off the portion that had the kink as well as moving the cable modem leg from the -7dB output of the 3-way to the -3.5dB output.  Downstream moved from -5/-7 to -1/-3, and upstream fell further to 44dBmV.

I thought that had fixed it, but this morning it spontaneously rebooted again.  This time, re-establishing the sync tool a minute instead of the 15-20 mins of before.  It had been up for 14 hours which is a record compared to recent history.  I will check again when I get home, but unless periodic rebooting is normal, I still have some sort of problem.

FWIW, downstream S/N is consistently 37dB.

[andyross]

The maximum upstream strength actually depends on the type of modulation used. In the past, you could see 60dB, but that is with QAM16 or QPSK. I believe QAM64 maxes out around 57-58.

[EG]

Taken from the FAQ at the BBR Forums;

Upstream (Tx) Transmit Power (a.k.a. Return Signal) level:
This is the amount of signal transmitted by the modem to reach the receiver in the cable company head-end.

+8 dBmV to +58 dBmV maximum for QPSK. (DOCSIS 1.0, 1.1)
+8 dBmV to +55 dBmV maximum for 8 QAM and 16 QAM. (DOCSIS 1.0, 1.1)
+8 dBmV to +54 dBmV maximum for 32 QAM and 64 QAM. (A-TDMA DOCSIS 2.0)
+8 dBmV to +53 dBmV maximum for S-CDMA DOCSIS 2.0 (All Modulations)

*Recommended upstream signal levels are +35 dBmV to +52 dBmV.


[pepar]

Did not see DOCSIS 3.0 there, but they all look similar so it's likely 3.0 is inline with the previous versions.

Just checked my modem's home page and system uptime is about 21 mins, so it must have rebooted recently.

And so it goes.

Jeff

[andyross]

I do think I remember seeing that D3 modems can be 2dB higher on upstream.

[pepar]

Perhaps, but the fact remains that the Motorola tech told me that my D3 modem could operate up to 58dBmV upstream but would start being overdriven at levels over 50.

[pepar]

Googling the error messages re timing out and no ranging response received yields hundreds of posts from people withe same issues, many on comcast. I am going to continue that searching/reading, but it looks like it is not anything in my house but is a comcast problem. Quite a few posters express frustration at getting comcast to acknowledge that I is their problem. I myself have replaced my modem three times. Router three times, and in what seems like a huge waste of resources comcast techs have replaced every connector from the pole to my cable modem, and replaced splitters.

My secretary is new to comcast Internet and she says that she gets "server not found" messages. She's not tech savvy, but tha means that here modem has lost sync. All she has gotten from comcast is the automated message to turn off and reboot her modem and router. As far as I am concerned, this is a waste of time that non-technical people are put through.

I am an unhappy comcast customer who is wasting his time trying to learn enough about the subject so that I can speak intelligently to comcast tech support and not get blown off like my secretary.

[Davenlr]

I can tell you one thing.  It is NOT the modem.  I had this problem with THEIR modem.  Bought my own cheap Zoom modem, still had problem.  Returned that one, and bought the top of the line, on the list, Motorola Docsis 3.0 modem, SAME PROBLEM.  Tech coming out tomorrow morning.  Will report back with any results.

[Davenlr]

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b-slice wrote:

Any updates?   I am also having this same issues (swapped out 2 modems as well to eliminate issues on my side)

---

Yep, I have an update.   I wrote the VP of Comcast for our local franchise, and she sent a line tech out, who spent all day checking all the lines, etc (or so I was told).  After he was finished, my internet would go out for an hour or 2 instead of 5 minutes, and about 4 times a day.  It was basically useless.

I got mad, and disconnected the splitter, ran the coax directly into the modem on Friday afternoon.  As of Monday morning, my modem had not dropped connection once.

I unplugged the cablecards from my two Tivos, packed up the DTA, and drove to the local office and canceled my TV service.   They told me they would raise my Internet service $15 by not having TV.  I explained they could not get both to work at the same time, and got the "sorry, to bad".   Passed that info onto the VP, and Ill just say she took care of me.

So, in my case, apparently they just could not get enough signal through my 20 yr old drop from the house to the street to overcome that extra 3.5db the splitter was dropping it.   Of course, they never bothered to replace the drop with new coax, or connectors (even though I told the VP that several trucks had hit the line and ripped it off the house).   No one even checked it for damage.

I am now happily watching DirecTv, and surfing with Xfinity.  My modem has rebooted once since I dropped the TV.

[pepar]

My saga has another episode about to happen this coming Tuesday.  Some background first .. just before the last tech visit two weeks ago, I started eyeballing my installation and noticed a very tight radius in the RG6.  As the problem ... or at least one of them was that the upstream signal was too high and was driving it into distortion, that seemed like a possible culprit.  Nevermind that five or six techs came and went and never spotted it.  But this guy fixed it and IMMEDIATELY the signal level dropped back into a comfortable range.  Golden I thought.

But not long after he left, my modem spontaneously rebooted again.  The difference is that it now reboots in under a minute instead of the 5-10-20 minutes from before.

My last tech support was a few days ago and while I was on the phone, and while my modem lights were all lit, the rep reported to me that my modem was off line.  He ran some tests and cut and pasted the results into the trouble ticket.  This Tuesday, a tech is supposed to come and check THE LINES between me and the head end.

That *seems* like progress, but it has been two years.

Jeff

[cybervang]

Have you guys tried using MANUAL on the Domain Name Server DNSnstead of using AUTO?

Sometimes some routers can have issues trying to refresh or retrieve from AUTO DHCP & that causes timeouts on Cable Modems, stalls, & sometimes reconnects.

Hope it works for you.

[pepar]

My follow-up is that the tech called me this morning and related that he had been on a conference call regarding my node and that something was done .. replaced something I think .. that had been causing high S/N and modems to reboot spontaneously.  He offered to come to my house anyway, but I said that I would go with this and see if the problem was still happening.  I did use it the rest of the morning with no problems.  we had a power outage this evening, so the uptime clock reset 3+ hours ago.  I'll check it again tomorrow morning, but it had been happening so often before that I think it would have happened by now if it were going to happen.  I'll know in another day ....

Jeff

[EG]

---

cybervang wrote:

Have you guys tried using MANUAL on the Domain Name Server DNSnstead of using AUTO?

Sometimes some routers can have issues trying to refresh or retrieve from AUTO DHCP & that causes timeouts on Cable Modems, stalls, & sometimes reconnects.

Hope it works for you.

---

FWIW, this older thread is mainly about and discussing RF signal/connection quality issues which are not directly related to DNS issues.

[EG]

---

pepar wrote:

My follow-up is that the tech called me this morning and related that he had been on a conference call regarding my node and that something was done .. replaced something I think .. that had been causing high S/N and modems to reboot spontaneously.  He offered to come to my house anyway, but I said that I would go with this and see if the problem was still happening.  I did use it the rest of the morning with no problems.  we had a power outage this evening, so the uptime clock reset 3+ hours ago.  I'll check it again tomorrow morning, but it had been happening so often before that I think it would have happened by now if it were going to happen.  I'll know in another day ....

Jeff

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Best of luck with it !

[pepar]

Whatever they did did not fix the problem.  But the most recent tech passed along my situation to his supervisor and I have heard from someone, I believe, in line maintenance.  The nature of my problem seems to point to something up the line, but I don't know what that would be.  One of the new tricks is for the cable modem to be completely sync'd and no data throughput.  Two calls ago to Comcast, the person was looking at my being offline while I was looking at all of the lights indicating all's well.  He pinged and lost 10/10, and then cutand pasted that into the report.

Jeff

[J95cccDc2011]

Has anyone found a solution to this problem?  I can't afford have this kind of increasingly worse disconnections.  I have fair inclination from the rumor that this is Comcast issue.  I think this is how they manage the limit on their available bandwidth at the risk of losing customers.