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T3 and T4 errors

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Frequent Visitor

T3 and T4 errors

Im getting a lot of t3 and t4 errors. My modems event log has tons of them. Anyone know the cause and solution? Tia!
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Gold Problem Solver

Re: T3 and T4 errors

Please see Internet Troubleshooting Tips. If you still need help, please post your modem or gateway's model number and signal information, especially downstream power levels and SNR, upstream power levels, and error log.

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Frequent Visitor

Re: T3 and T4 errors

Its a netgear cm400. Its not giving me a option to view power levels or signal information. This is my event log. Thanks for the help!
https://drive.google.com/file/d/10jvZWeZVMisqLnvAqq1rxBjcjuTT7Sem/view?usp=drivesdk
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Gold Problem Solver

Re: T3 and T4 errors


@xnewmanx wrote: Its a netgear cm400. Its not giving me a option to view power levels or signal information. ...

Please see https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router or the modem's User Guide at http://www.downloads.netgear.com/files/GDC/CM400/CM400_UM_EN.pdf

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Frequent Visitor
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Gold Problem Solver

Re: T3 and T4 errors


@xnewmanx wrote: Thanks! Heres the link ...

The downstream numbers look OK although the error counts seem a bit high, but the upstream power level is too high (should be less than 51 dBmV) and only one upstream channel is locked (should be at least 3). Problems like this are often due to poor coax connections or damaged coax cable, usually in or near your home.


If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips.


If you can't find the problem or you'd rather have Comcast take care of it, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. Insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have their Service Protection Plan (https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device, or anything outside your home, you shouldn't be charged.

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Frequent Visitor

Re: T3 and T4 errors

Thanks Bruce. I'll go check all my coax connections and cable from the box into the house. I do have 1 splitter between the box and the house, I may just go ahead and pick up a new one just to rule that out. This has only been happening in the last 3 weeks or so.
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New Poster

Re: T3 and T4 errors

I'm going to highly recommend that you replace that retired CM400 with something more reliable and capable of faster data rates.  I would consider the Motorola MB7420 or MB7421 which are made by Zoom and are fairly affordable.  They MB7420 operates on 16 downstreams and the MB7421 used 24 downstreams for much faster download speed capability.

 

Tx power 54 and single Tx bonded on an older Docsis 3.0 isn't suprising.  The Arris 6182 which is also a 8 downstream modem also exhibited this behavior when it's beginning to fail.  High Tx can sometimes be caused by a faulty amp, poor connectors, upstream interference in the street and too many splitters.  But in your case, I'm fairly certain it's the CM400's fault.

 

Also, the CM400 is limited to around 300Mbps with only 8 downstreams so you may be missing out if you subscribe to the newer Comcast service tiers.

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Frequent Visitor

Re: T3 and T4 errors

It ended up being a faulty splitter in the cable box outside that I didnt even know was there. Thanks for all the help!
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Gold Problem Solver

Re: T3 and T4 errors


@xnewmanx wrote: It ended up being a faulty splitter in the cable box outside that I didnt even know was there. ...

Glad you got it, and thanks for letting us know what the problem was!

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Frequent Visitor

Re: T3 and T4 errors

No problem, hopefully this helps someone else.