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DominoToppler
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23 Messages

Sunday, November 15th, 2020 8:00 AM

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Losing internet repeatedly

Hello, for the last two days, our internet has gone out for several hours. The troubleshooting function of the XFi app is unable to reach the XB7 to send a reset signal. Yesterday I contacted ComcastCares on Twitter and they were going to try and help from their end, but I think it came back spontaneously before they really did anything.

I have a blinking green light on the XB7. Cable TV still comes through, but the boxes don’t have network connectivity since the internet is down. I can connect to the WiFi network, but neither wired nor Wi-Fi devices have a connection.

I am attaching a screenshot from the admin panel. Basically (in case the image isn’t immediately viewable) it shows the following. I have tried swapping the coax cable from the wall to a Comcast provided cable. So now it’s a Comcast provided cable going to a Comcast provided splitter, going to two more Comcast provided cables, one to the XB7 and one to the 4K DVR box. All the cables and splitters are less than a month old.

Initialization Procedure
Initialize Hardware:NotStarted
Acquire Downstream Channel:NotStarted
Upstream Ranging:NotStarted
DHCP bound:NotStarted
Set Time-of-Day:NotStarted
Configuration File Download:NotStarted
Registration:NotStarted
Cable Modem
HW Version:2.0
Vendor:Technicolor
BOOT Version:S1TC-3.63.20.104
Core Version:1.0
Model:CGM4331COM
Product Type:XB7
Flash Part:8192 MB
Download Version:Prod_19.3_d31 & Prod_19.3
Serial Number:304930030371112595
Downstream
Channel Bonding Value
Index
17
Lock Status
Locked
Frequency
579 MHz
SNR
41.0 dB
Power Level
-6.8 dBmV
Modulation
256 QAM
Upstream
Channel Bonding Value
Index
1
Lock Status
Not Locked
Frequency
35 MHz
Symbol Rate
5120
Power Level
59.0 dBmV
Modulation
QAM
Channel Type
ATDMA
CM Error Codewords
Index
1
Unerrored Codewords
6462525
Correctable Codewords
0
Uncorrectable Codewords
0

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Question

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Updated 

5 years ago

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DominoToppler

Contributor

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23 Messages

5 years ago

Thanks I have checked and double checked all connections, swapped out the one splitter I know of, and I remain with the same issue. Very odd and frustrating considering that I never had these issues with my SB8200... only since switching to the XB7.

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EG

Expert

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111.5K Messages

5 years ago

The upstream power is way out of spec and the downstream power is on the weak side. 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.

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DominoToppler

Contributor

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23 Messages

5 years ago

Now it has changed slightly to the below:

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DominoToppler

Contributor

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23 Messages

5 years ago

Keeps intermittently changing. I should mention I have had a rock solid connection for years on Gigabit with my own SB8200 modem and didn’t start having issues until I switched to the XB7 and got a cable TV subscription, and more specifically a week or so after that when we had a pair of hurricanes and I had service go out for 5 days due to a problem at a nearby node.

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EG

Expert

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111.5K Messages

5 years ago

Then you'll need to book a tech visit. 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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DominoToppler

Contributor

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23 Messages

5 years ago

Holy cow, so after thoroughly cleaning the cable termination behind the wall going into the wallplate coupler, I now have service again! Can you please tell me if these numbers are okay now or should I still book a tech visit?

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DominoToppler

Contributor

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23 Messages

5 years ago

Thank you EG. I have been fiddling around with cleaning connections and my numbers have changed slightly. Can you please tell me if these are better/worse?

I think part of the reason I am having issues now versus before when I just had an SB8200, is that I also added cable TV. So now I have the XB7 plus a cable box attached to the same outlet, meaning that another splitter had to be added to the system by necessity.

Now what I did prior to these latest readings is remove the wall plate (it’s just a wall plate with coax coupler) and cleaned some of the corrosion on the old coax cable that was behind the wall. It looked pretty oxidized... I used isopropyl alcohol on a Q-tip to try and clean it... not sure if there’s something better.

Anyway, here’s the latest numbers and thank you again very much for your help!!

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EG

Expert

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111.5K Messages

5 years ago

Quite welcome ! Good luck with it ! Here's what the specs should be;

 

Specification      Min             Max

Downstream Power Level  
Cable Modems-10dBmV+10dBmV
Gateways and EMTAs-7dBmV+7dBmV
Downstream Signal to Noise Ratio35dB-
Upstream Power Level+35dBmV+50dBmV
Upstream Signal to Noise Ratio31dB-
Upstream Receive Power-2dBmV+2dBmV

 

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EG

Expert

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111.5K Messages

5 years ago

It's still n/g.

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DominoToppler

Contributor

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23 Messages

5 years ago

Bummer... what a pain... thanks for your time.

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