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ewoj104
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Tuesday, May 19th, 2020 11:00 AM

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Bad Coax Cable?

Hello,

 

I have been fighting slow speeds to my modem for a few weeks now (paying for 600 mbps, getting 33 max when hardwired). I eliminated any splitters that I could, bring it down to just one splitter which splits between the modem and the TV box.   I called a few days ago and at first i had the automated help which forced a modem reboot, and the reboot fixed it for about 12 hours, but then i was back to 33. I called again the next day and the tech said I had an upstream/downstream problem and sent me a new modem. I swapped out the modems and the problem continues.  I tried putting the modem in place of the tv box temporarily and i actually get good speeds when it is in that spot, which makes me think it is the coax cable from the splitter to my modem.  I would just replace the cable, but it goes through several walls and up two floors on the back of the house, so its not an easy thing to do.

 

So two questions.  1) If this is a bad coax cable, does comcast replace those or do they only handle the ones up to the house?  2) If it is a bad cable, how was it able to get good speeds for 12 hours after the reboot?  FYI ive done plenty of manual reboots myself and did not have the same luck.

 

Any guidance would be appreciated! Thanks.

Question

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Updated 

5 years ago

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PLCMAN

Contributor

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36 Messages

5 years ago

1. Are you using the correct splitter for Compcast?

2. Do you have any unterminated ports on the splitter?

3. Do you have a power supply plugged into the splitter to power the fiber optic hardwre if have fiber to your house?

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EG

Expert

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110.4K Messages

5 years ago

@ewoj104 wrote:

Hello,

 

I have been fighting slow speeds to my modem for a few weeks now (paying for 600 mbps, getting 33 max when hardwired). I eliminated any splitters that I could, bring it down to just one splitter which splits between the modem and the TV box.   I called a few days ago and at first i had the automated help which forced a modem reboot, and the reboot fixed it for about 12 hours, but then i was back to 33. I called again the next day and the tech said I had an upstream/downstream problem and sent me a new modem. I swapped out the modems and the problem continues.  I tried putting the modem in place of the tv box temporarily and i actually get good speeds when it is in that spot, which makes me think it is the coax cable from the splitter to my modem.  I would just replace the cable, but it goes through several walls and up two floors on the back of the house, so its not an easy thing to do.

 

So two questions.  1) If this is a bad coax cable, does comcast replace those or do they only handle the ones up to the house?  2) If it is a bad cable, how was it able to get good speeds for 12 hours after the reboot?  FYI ive done plenty of manual reboots myself and did not have the same luck.

 

Any guidance would be appreciated! Thanks.

What do the modem's signal stats look like at the original coax outlet ?  Try getting them here http://192.168.100.1 or here http://10.0.0.1

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


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ewoj104

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2 Messages

5 years ago

Im not sure if it is an official splitter or not. Im guessing it would have a big comcast sticker on it? If so then no, it is not an official splitter (however when comcast was here setting it up originally they didnt question the splitter at all. this splitter came with the house).  No unterminated ports in my current setup. I do not have fiber to the house.

 

Here is the upstream and downstream for the modem location:

Index 1 2 3
Lock Status Locked Locked Locked
Frequency 36 MHz 30 MHz 23 MHz
Symbol Rate 5120 5120 5120
Power Level 51.5 dBmV 51.5 dBmV 51.5 dBmV
Modulation QAM QAM QAM
Channel Type ATDMA ATDMA ATDMA

 

Index 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 30 31 32 159  
Lock Status Locked Locked Locked Not locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Not locked Locked Locked Locked Locked Locked Locked Locked
Frequency 651 MHz 477 MHz 483 MHz 489 MHz 495 MHz 507 MHz 513 MHz 519 MHz 525 MHz 531 MHz 537 MHz 543 MHz 549 MHz 555 MHz 561 MHz 567 MHz 573 MHz 579 MHz 585 MHz 591 MHz 597 MHz 603 MHz 609 MHz 615 MHz 621 MHz 627 MHz 633 MHz 639 MHz 645 MHz 657 MHz 663 MHz 669 MHz 678 MHz 617600000
SNR 33.0 dB 36.9 dB 29.0 dB 0.0 dB 27.4 dB 35.5 dB 38.5 dB 38.2 dB 38.7 dB 41.2 dB 41.0 dB 41.0 dB 40.3 dB 36.4 dB 39.4 dB 41.1 dB 41.7 dB 41.4 dB 40.8 dB 39.4 dB 40.2 dB 39.5 dB 35.8 dB 32.8 dB 35.4 dB 31.0 dB 0.0 dB 32.5 dB 30.6 dB 38.5 dB 38.8 dB 37.6 dB 38.0 dB NA
Power Level -18.6 dBmV -16.3 dBmV -21.6 dBmV -31.6 dBmV -26.3 dBmV -17.1 dBmV -13.9 dBmV -14.4 dBmV -13.4 dBmV -9.9 dBmV -10.1 dBmV -10.2 dBmV -9.7 dBmV -7.8 dBmV -8.7 dBmV -9.9 dBmV -8.9 dBmV -9.1 dBmV -10.1 dBmV -12.5 dBmV -11.1 dBmV -12.1 dBmV -16.6 dBmV -20.0 dBmV -17.2 dBmV -20.6 dBmV -27.2 dBmV -20.3 dBmV -21.9 dBmV -13.1 dBmV -12.7 dBmV -14.1 dBmV -8.6 dBmV NA
Modulation 256 QAM 256 QAM 256 QAM Unknown 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM Unknown 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM OFDM

OFDM

 

 

 

And for reference, here is what i get when the modem is at my cable box location:

 

Index 1 2 3
Lock Status Locked Locked Locked
Frequency 36 MHz 30 MHz 23 MHz
Symbol Rate 5120 5120 5120
Power Level 47.5 dBmV 47.5 dBmV 49.3 dBmV
Modulation QAM QAM QAM
Channel Type ATDMA ATDMA ATDMA

 

Index 9 1 2 3 4 5 6 7 8 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 159  
Lock Status Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked Locked
Frequency 531 MHz 477 MHz 483 MHz 489 MHz 495 MHz 507 MHz 513 MHz 519 MHz 525 MHz 537 MHz 543 MHz 549 MHz 555 MHz 561 MHz 567 MHz 573 MHz 579 MHz 585 MHz 591 MHz 597 MHz 603 MHz 609 MHz 615 MHz 621 MHz 627 MHz 633 MHz 639 MHz 645 MHz 651 MHz 657 MHz 663 MHz 669 MHz 678 MHz 617600000
SNR 41.7 dB 42.4 dB 40.1 dB 41.3 dB 41.8 dB 40.9 dB 41.7 dB 41.9 dB 41.8 dB 42.0 dB 41.9 dB 40.5 dB 36.4 dB 40.1 dB 42.0 dB 42.1 dB 41.8 dB 42.1 dB 41.9 dB 42.3 dB 42.2 dB 41.9 dB 41.9 dB 41.9 dB 42.0 dB 41.9 dB 41.6 dB 41.9 dB 41.7 dB 41.8 dB 41.7 dB 41.4 dB 40.1 dB NA
Power Level -5.5 dBmV -4.7 dBmV -6.0 dBmV -4.6 dBmV -5.5 dBmV -5.0 dBmV -5.9 dBmV -5.1 dBmV -5.1 dBmV -4.9 dBmV -5.1 dBmV -5.2 dBmV -4.4 dBmV -5.1 dBmV -4.4 dBmV -4.7 dBmV -5.0 dBmV -4.4 dBmV -4.7 dBmV -4.1 dBmV -4.3 dBmV -5.1 dBmV -4.5 dBmV -4.8 dBmV -4.3 dBmV -4.6 dBmV -5.2 dBmV -4.1 dBmV -5.1 dBmV -4.6 dBmV -4.9 dBmV -5.1 dBmV -4.4 dBmV NA
Modulation 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM 256 QAM OFDM OFDM

 

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CCAndrew

Gold Problem Solver

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25.9K Messages

5 years ago

The first location, either the cable is garbage or you have an additional splitter somewhere

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EG

Expert

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110.4K Messages

5 years ago

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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