shane_ermitano's profile

New Poster

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4 Messages

Mon, Jan 11, 2021 7:00 AM

Connectivity issues

Modem: NETGEAR CM1200

Wireless Router: TP-Link Deco M5

 

Started two days ago. Our network suddenly went down.

 

Comcast technician came yesterday to inspect the line, said it was all good and that it was probably my modem. Spent an hour+ with Netgear trying to diagnose my issues, hardwiring back into the modem with a single computer brought the connect back online.

 

Set my network back up with wireless router. Woke up this morning to the network back down.

 

Checked the modem logs and found this:

  • Critical (3) "Started Unicast Maintenance Ranging - No Response received - T3 time-out;"
  • Critcal (3) "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;"
  • Warning (5) "Lost MDD Timeout;"

Screenshots from modem logs here: https://imgur.com/a/VLyp2Ct

Responses

EG

Expert

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87.1K Messages

5 m ago

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


New Poster

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4 Messages

5 m ago

EG

Expert

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87.1K Messages

5 m ago


@shane_ermitano wrote:

*SNR* (Signal to Noise Ratio)
How do I find this?

The SNR values are listed in the same place where the downstream power levels are listed. Please post a screenshot of all of the signal status page or copy all of the text and paste it into the body of your next post here.

New Poster

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4 Messages

5 m ago

*Downstream Power Level*
-1.1 dBmV - 40.2 dB

*Upstream Power Level*
56.5 dBmV

New Poster

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4 Messages

5 m ago

There are no splitters in the home. A tech came out yesterday and didn't find anything unusual.

Should I book another appointment?
EG

Expert

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87.1K Messages

5 m ago

I see that you edited your post.. Disregard my last reply.

 

The upstream power too high / out of spec. 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.

EG

Expert

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87.1K Messages

5 m ago

The 49 is better than the 56 but it's still on the high end. It shouldn't be making such wide intermittent swings like that ! If there is nothing that you can do from those tips then yes, get the techs re-involved until it is fixed properly. Try to show them this thread.

 

Also, bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.
Good luck !

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