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Strangely disconnecting internet

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Strangely disconnecting internet

Hello -

 

I began service with xfinity in January, and it worked fine for months with a CM500 I purchased off of Amazon.  Last month it suddenly stopped working - no cord jostling, no service outages.  Rebooting and web troubleshooting didn't help, and the technician that came out was fairly stumped until we tried re-initializing it like it was a new device, which strangely worked.  After another month of fine internet, suddenly it has disconnected itself again.  This time even re-initializing isn't helping, assuming the support technician I spoke to on the phone did it correctly.  I'm a bit stumped because otherwise the modem seems fine, and it worked for so long.  If  technician comes again to my house and finds that the problem is my hardware (which he may claim if he can't figure it out since it's easy to blame) it's $70, more than the cost of just buying a new modem.  But the modem worked fine for so long, and even worked again after this problem happened the first time.  Anyone have ideas or have encountered this before? 

Modem logs show errors like 'No Ranging Response received - T3 time-out' and 'TLV-11 - Illegal Set operation failed' and 'SYNC Timing Synchronization failure - Failed to acquire FEC framing' which I assume are standard errors that mean 'not connecting'.  Also it shows:

Acquire downstream channel:  633000000 Hz  Locked
Connectivity State:    In Progress   Params Transfer Complete

Boot State:                   In Progress  Unknown
Security:                       Disabled       Disabled
UP Provisioning mode:  In Progress  Unknown

Downstream Bonded Channels:

1 Locked QAM256 25 633000000 Hz -2.3 dBmV 35.4 dB 0 0

 

Upstream Bonded Channels:
1 Locked ATDMA 19 5120 Ksym/sec 23000000 Hz 39.3 dBmV

Any help appreciated...

Contributor

Re: Strangely disconnecting internet

If you only have one downstream and one upstream locked channels, you have a serious problem.  You would need a tech visit to diagnose that.  It is possible your modem is losing its provisioning.  Your modem has what is called a "boot file".  When you call comcast have them check if that is correct.  If not, maybe have severe signal problems causing your trouble.  At that point a good tech visit would be helpful.  Hope someone can help.  Your modem is a 16 x 4 Docsis 3.0 modem, which means you should see 16 downstream channels and 4 upstream channels (some markets are only using 3 upstream channels, so be aware of that if you only see 3).  Obviously something is amiss.....

Expert

Re: Strangely disconnecting internet


@KirkBays wrote:

 

 

 and the technician that came out was fairly stumped until we tried re-initializing it like it was a new device, which strangely worked. 

 

If  technician comes again to my house and finds that the problem is my hardware (which he may claim if he can't figure it out since it's easy to blame) it's $70, ..


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. Good luck !



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