Comcast / Motorola sb5100 cable modem dropping connection...

b4serenity · 2006-05-10T12:37:36+00:00

I have broadband cable internet service from Comcast and I've been veryhappy with it until this past week. I've been having intermitantservice to the net and it's really bugging me! It will work fine andthe online light will be on the external modem and then it will just beoff and no internet for my family (and biz). Then, it will just comeback on again after a few minutes, maybe stay on for hours then offagain for awhile.I've talked to Comcast and we did a powerdown reset on the computer andmodem and he could tell on his end what my modem was trying to do (butnot succeeding in doing = to get online) and he said that the signalwas good to the house and that many people on my street were on at thatvery moment w/o any complaints. He had me test the cable channels andthey were all fine as well. A new (mega thick) line was run to ourhouse just a few months back (worked fine after the cable wasinstalled). So he said it must be the modem.We own our modem so they offered to have us signup for their rentalservice ($3?/mo) but he wasn't sure if there would be a service/installation fee to deliver and set it up. I told him I'd just buyanother one myself.Am I smart in doing this or should I just pay their fee and have themdo it so the servicing is all on them? I worry (and have heard about)about them using some cheap modems that actually don't work as reliablyor as fast as the Moto Surfboard SB5100 that I now have. Yes, the ironyof that last staement about my modem being reliable has hit me!I have some info (an error log and some specific numbers but I'm notsure which ones are relevent here) from a Motorola diagnostics site ifthat could help anybody help me.Before I fork over my money on a new modem could it be anything else?Thanks so much for the help!!!!

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Dave 20 years ago

I had a similar situation a couple years ago. Everything was fine and then it'd go offline for 15 minutes to a few hours. Of course, when I reported it they'd schedule a service call and all would be well by the time he showed up 2 days later. Later another outage and the same problem. I finally got so frustrated that I went to the local Comcast office, spoke to the manager and described my frustration. She contacted the local maintenance manager who called me to discuss it. They finally realized they had an amp with an intermittent noise problem. They changed the amp and it hasn't happened since.

If I were you, I'd be escalating the issue and talking to a higher level of management. In that kind of situation the normal trouble reporting process is unlikely to work and you'll have to become the squeaky wheel. I'd keep escalating until you get someone's attention.

That's just my two cents worth.......

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b4serenity 20 years ago

I just talked with others on my street w/ comcast net service and they've been fine. So, now that, with the fairly OK signal strength shown, has me thinking more then ever that it's probably the modem. I'll give it a shot and see if that does the trick. If it doesn't fix it then s the ball will be back in comcast's court.

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Ed Nielsen 20 years ago

I had a situation that started around the end of January that nobody could figure out. Talked with my assistant state engineer a few times about it and nothing made any sense. Levels were great and S/N was great also. Download speeds suddenly dropped to about 1/3 of what they were previously. Swapped the modem out with one I had previously with no change. Upload was not affected, just download. Went on for a couple of months. Eventually, a Chief Tech in Indiana mentioned something. I bought a new cable modem and voila, back in business.

CIAO!

Ed N.

snipped-for-privacy@gmail.com wrote:

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b4serenity 20 years ago

No new modem yet but here's the latest error log; Does this indicate a bad signal from Comcast or still possibly a Modem problem? Any help appreciated!!

Time Priority Code Message

2006-05-12 17:46:54 3-Critical R002.0 No Ranging Response received - T3 time-out 2006-05-12 17:46:44 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing 2006-05-12 17:46:24 3-Critical R002.0 No Ranging Response received - T3 time-out 2006-05-12 17:46:04 3-Critical R007.0 Unicast Ranging Received Abort Response - Re- initializing MAC 2006-05-12 17:45:47 3-Critical R002.0 No Ranging Response received - T3 time-out 2006-05-12 17:45:42 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing 2006-05-12 17:45:21 3-Critical R002.0 No Ranging Response received - T3 time-out 2006-05-12 17:45:07 3-Critical R007.0 Unicast Ranging Received Abort Response - Re- initializing MAC 2006-05-12 17:44:49 3-Critical R002.0 No Ranging Response received - T3 time-out 2006-05-12 17:44:43 3-Critical R007.0 Unicast Ranging Received Abort Response - Re- initializing MAC 2006-05-12 17:41:28 3-Critical R005.0 Started Unicast Maintenance Ranging - No Response received - T3 time-out 2006-05-12 13:25:23 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing 2006-05-12 13:25:19 3-Critical T002.0 SYNC Timing Synchronization failure - Failed to acquire FEC framing 2006-05-12 13:25:19 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing 2006-05-12 13:25:14 3-Critical T002.0 SYNC Timing Synchronization failure - Failed to acquire FEC framing 2006-05-12 13:25:12 3-Critical T001.0 SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing 2006-05-12 13:25:12 3-Critical T002.0 SYNC Timing Synchronization failure - Failed to acquire FEC framing 2006-05-12 13:25:11 3-Critical T001.0 SYNC Timing Synchronizatio

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Ed Nielsen 20 years ago

I don't really know much about log entries, but mine often indicates "3-Critical R02.0 No Ranging Response received - T3 time-out."

With your numbers being what they are (especially the SNR) and the fact that no neighbors are experiencing the same issues (especially if 1 of them is connected to the same tap (cable goes to the same pedestal as yours), the cable modem seems to be the most likely culprit.

CIAO!

Ed N.

snipped-for-privacy@gmail.com wrote:

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$Bill 20 years ago

Geez - if you know your neighbors that well, swap modems with one of them and see what happens.

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Ron W 20 years ago

Sorry I can't help -- I started having similar problems a couple of days ago with my Motorola SB 5120 -- occasionally "Send Channel" light flashes. I suspect I can improve my situation with a little reduction in cable losses. My question: How do you access the cable signal levels? Is it available via a URL? Thanks.

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Bit Twister 20 years ago

http://192.168.100.1

Values from mine: Motorola Surboard SB5120 QAM 256 (Working range) Down Power -3 dBmV (-10 and +10 dBmV) SNR 37 dB (higher than 33dB) Up Power 47 dBmV (30 and 55dBmV)

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Ron W 20 years ago

Thanks for your help. My levels: Downstream = -6 dBmV Upstream = 54 dBmV. I still want to reduce losses to get the downstream level up closer to mid-range.

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$Bill 20 years ago

I'd be more worried about your *shouting* upstream. Try to remove any extra splitters and such and make sure you have RG6 cable and tight connections and if no help there, call them out to look into lowering your upstream.

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Andrew Rossmann 20 years ago

In some cases, you may be able to use a tab instead of a splitter. For a tap, the 'out' port will have little to no loss. The 'tap' port will have 6db or so of loss (a splitter typically has 3.5db loss on both output ports). That may be OK for analog TV's or even digital if the signal is strong enough.

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lawrence.jones 20 years ago

There's no such thing as a free lunch. Unless one port has no signal at all, there's always going to be *some* loss at both ports.

-Larry Jones

Hmm... That might not be politic. -- Calvin

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Roy 20 years ago

go to 192.168.100.1 from your browser, you should get the modem configuration manager. You cah look at signal and other things there.

Roy

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steve 20 years ago

snipped-for-privacy@ugs.com wrote in news: snipped-for-privacy@jones.homeip.net:

splitter.

signal

You are right a tap, or a directional coupler is simply a splitter that has a bias on one of the through legs, usually 1 but it increases with the frequency, as much as 3 on 860 MHz. Usually a DC has a value of 6 or

9 as a normal 2 way splitter has a value of 3.5. You want to use the TAP leg as the minimal drop leg. 53 on the test subjects modem is fine, they can go as high as 63.

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sgoldman 20 years ago

I had Comcast out this week for my chronic connectivity issues. The tech said the Motorola modems (mine's a Surfboard 5100) are set to shut themselves off at 54dB upstream. When the upstream power is high, says my tech, the problem is at the pole and Comcast needs to come out and 'rebalance' their side. So while going to a tap (good suggestion!) or disconnecting your splitter will buy you a few dB to stay online, you need to get Comcast out there to do their side of the pole.

I demanded a second cable drop (a dedicated coax run from the pole to my modem, separate from the TV cable into my house) last year when I had similarly frustrating cable issues.

The good news: Verizon is wiring my neighborhood (Livingston, NJ) for fiber-to-the-house, and should be turning on the switch for their verizonfios service here in the next two months, according to the techs working on the street. As soon as that happens, it's goodbye Comcast for me. Say what you will about the phone company, but my dial tone never drops, and my cable is out at least twice a month. Ciao, Comcast!!!

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