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T3 Timeouts -- is my modem going bad?

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Regular Visitor

T3 Timeouts -- is my modem going bad?

I'm having short but annoying intermittent outages.  Like others, I see intermittent T3 time-out errors in the logs -- they come in bunches at different hours of the day, but they don't always correspond to outage periods.  I've checked cables in my house, but there are plenty outside on the telephone poles and in the cable box that I can't check.


Question: 

When I'm having a outage, the modem website 192.168.100.1 barely responds.  I'm trying to see the signal strength page during an outage but the modem doesn't return that page.  I've only seen high signal strength once.  Could this be a sign that the modem itself is going bad and causing the problems?

 

The modem is an ARRIS SURFboard SB6121 bought 5 years ago.  Any suggestions appreciated.

 

Thanks.

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Expert

Re: T3 Timeouts -- is my modem going bad?

Start with the modem's signal stats. Perhaps they already are, or they are close to being out of spec and intermittently they go completely of spec. Try getting them here http://192.168.100.1 

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.




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Regular Visitor

Re: T3 Timeouts -- is my modem going bad?

Here are the values.  Do they look like they are out of spec?


Downstream Bonding Channel Value
Channel ID 9 10
Signal to Noise Ratio 34 dB 31 dB
Power Level
-9 dBmV -9 dBmV

 

Upstream Power Levels:

Power Level 37 dBmV 39 dBmV 38 dBmV 38 dBmV

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Expert

Re: T3 Timeouts -- is my modem going bad?

The downstream power is almost out of spec and it may be intermittently fluctuating even lower to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.



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Regular Visitor

Re: T3 Timeouts -- is my modem going bad?

Thanks for the helpful reply!  What's an acceptable downstream power, maybe 0 dBm?

 

There's only one connect inside my house and no splitter (we're not using cable), so I think the problem must be outside where there's about 300ft of coax going up and down two telephone poles to the box on the ground.

 

I think I'd better ask for a technician to check things out.    

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Expert

Re: T3 Timeouts -- is my modem going bad?

Minus ten to plus ten is the desired range, with zero dB being right on the middle and perfect.


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