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Random Connectivity Loss

Regular Visitor

Random Connectivity Loss

Hello,

 

I've been having issues for the past few months with dropped connections. Typically what happens is, I'll be browsing normally for the majority of the time, but then a moment will come where my connection to the internet completely falls out, both for wi-fi and through ethernet. I've called the Comcast support line about half a dozen times now, and each time all I'll get is "power cycle the modem, we'll send reset signal" and then they refuse to address when I mention that I've done this before and it didn't solve anything.

This began happening when I was using a rented Comcast Router+Modem. I have since returned the hardware and moved to my own Router+Modem, which is a TP-Link TC-W7960. The device is whitelisted and connects to the internet, but I still have this issue where my connection will randomly be dropped, and it'll take anywhere from five to twenty minutes to reconnect. I've tried connecting to a different DNS server, but this issue stills occurs. The coax and ethernet cables are fine. There are no issues with the hardware, I can connect to the router through the local IP address while this is happening.

 

edit: These are the errors being logged in the Router+Modem whenever the connection is dropped.

Sat Apr 27 21:28:35 2019 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=7c:8b:ca:40:3f:2c;CMTS-MAC=00:01:5c:a2:b0:49...
Sat Apr 27 21:28:26 2019 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=7c:8b:ca:40:3f:2c;CMTS-MAC=00:01:5c:a2:b0:49;C...

 

Is there anything I can do to solve this? It is driving me insane, and I'm at wit's end with constantly being passed around on the help line, to the point that I'm considering moving to be able to change to another ISP (Comcast is the only thing available in this area.)

Expert

Re: Random Connectivity Loss

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




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Regular Visitor

Re: Random Connectivity Loss

@EG From the Router. They fluctuate throughout the day but for the most part they stay between -10dBmV ~ -5dBmV.

Downstream Bonded Channels:

Channel Status Modulation Channel ID Frequency Power SNR
1 Locked QAM256 7 549000000 Hz -9.7 dBmV 37.8 dB
2 Locked QAM256 1 513000000 Hz -5.5 dBmV 39.0 dB
3 Locked QAM256 2 519000000 Hz -5.2 dBmV 39.0 dB
4 Locked QAM256 3 525000000 Hz -6.3 dBmV 39.0 dB
5 Locked QAM256 6 543000000 Hz -8.5 dBmV 38.2 dB
6 Locked QAM256 8 555000000 Hz -8.7 dBmV 38.1 dB
7 Locked QAM256 9 561000000 Hz -6.0 dBmV 39.0 dB
8 Locked QAM256 10 567000000 Hz -5.5 dBmV 38.2 dB

 

Upstream Bonded Channels:

Channel Status Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 2 5120 ksym/sec 29600000 Hz 49.0 dBmV
2 Locked ATDMA 1 5120 ksym/sec 36100000 Hz 51.8 dBmV
3 Locked ATDMA 3 5120 ksym/sec 23000000 Hz 51.8 dBmV
4 Locked ATDMA 4 5120 ksym/sec 16500000 Hz 51.3 dBmV

 

Expert

Re: Random Connectivity Loss

The downstream power is on the weak side and the upstream power is on the high side and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.

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: Random Connectivity Loss

@EG 

Oh my goodness, thank you so much for this information, this is much more helpful than anything I got from the tech support line.

I'm in an apartment and don't have access to the cable layout, but I'll absolutely let the landlord know, since it's entirely possible that this is affecting other people in the same building. I've talked with Comcast and finally convinced them to send a technician out, which should happen tomorrow, I'll update if anything comes of it.

 

But on a fun side note, Comcast tried to call and cancel the technician appointment, because my connection "looks fine," despite my explaining that it's an intermittant failure that's impossible to manually replicate with my hardware. I think either way, I'm not going to be a Comcast customer much longer.

Expert

Re: Random Connectivity Loss

Good luck with it !



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Regular Visitor

Re: Random Connectivity Loss

Technician arrived yesterday. We peeked at the connection and found an extremely old, corroded splitter behind the cable outlet.

 

New Downstream/Upstream info, without the splitter. Looks like everything's closer to normal levels?

Channel Status Modulation Channel ID Frequency Power SNR
1 Locked QAM256 7 549000000 Hz 3.5 dBmV 41.9 dB
2 Locked QAM256 2 519000000 Hz 4.0 dBmV 42.0 dB
3 Locked QAM256 3 525000000 Hz 3.4 dBmV 41.9 dB
4 Locked QAM256 4 531000000 Hz 3.0 dBmV 41.7 dB
5 Locked QAM256 5 537000000 Hz 3.7 dBmV 41.9 dB
6 Locked QAM256 8 555000000 Hz 4.4 dBmV 42.5 dB
7 Locked QAM256 9 561000000 Hz 5.0 dBmV 42.5 dB
8 Locked QAM256 11 573000000 Hz 4.6 dBmV 42.5 dB

 

Channel Status Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 2 5120 ksym/sec 29600000 Hz 43.8 dBmV
2 Locked ATDMA 1 5120 ksym/sec 36100000 Hz 43.3 dBmV
3 Locked ATDMA 3 5120 ksym/sec 23000000 Hz 43.7 dBmV
4 Locked ATDMA 4 5120 ksym/sec 16500000 Hz 43.8 dBmV
Expert

Re: Random Connectivity Loss

Much better ! Hope things hold up for you ! Good luck !



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