[SOLVED] Mysterious Cable Internet Interruptions, Cable TV Not Affected

HellboP

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Aug 27, 2009
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Hey all. HellboP here again with another vague technical question.

My parents have been complaining about internet outages at their house for the past few months. I've checked some of the most obvious things and tried the usual amateur trouble shooting tricks to no avail. I've even called their cable provider (Comcast) and they weren't able to offer any solutions based on the "symptoms". I'll try to keep things concise here so I don't overload you with unnecessary information.

The Hardware:

Router: Linksys E3000
Modem: Motorola SURFboard SB6121

The Problem:

Cable internet service will disconnect. Seemingly no pattern to the time of disconnection or the duration. Both WiFi and ethernet affected on all devices (phones, tablets, desktops, etc). Cable TV is NOT affected.

What I've Tried:

  • Turning it off and on again (both the router and the modem)
  • Switching the coaxial cable
  • Switching to a different coaxial "tap"
  • Switching the ethernet cables
  • Updating the router firmware
  • Ensuring router settings are at those recommended by Tom's Hardware
Notes:

  • I'm not sure what their internet plan is. It might be relatively low speed, if that has any bearing on service availability.
  • There are a considerable amount of coaxial splitters used in their house by the time it reaches their TV and modem. It feeds in through the basement and splits a total of three times before it reaches the living room.
  • The house is almost 100 years old and I believe the cable was installed in the '70s.
I'm not sure if I should be requesting Comcast send a technician to the house at this point of if I'm just overlooking something trivial. They're willing to rent one of those all-in-one boxes from Comcast if it will fix their problems. Thanks for any feedback you can provide!
 

USAFRet

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Mar 16, 2013
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I had pretty much the same issue years ago.
Cable internet/TV.
Internet would cut out for hours, TV would be fine.

3-4-5 times a week.

Call the techs, they send someone out the next day.
All is fine.
Wash rinse repeat.
Eventually ALL equipment from the little interface box in the yard to my PC was replaced. Wiring, modem, etc, etc.

With the Cox modem, one could monitor the S/N ratio of the incoming signal...on their side of the modem.
Kept a log of exactly when it dropped.
It got so where I could predict the internet drop within a few minutes.

At one point, I had 3x Cox trucks and a supervisor out front, trying to diagnose.

Turns out, it was one of their upstream boxes partially dying due to temp/humidity. TV and internet being on different freqs, only the internet was affected.
 

kanewolf

Titan
Moderator
Simplest thing is to temporarily run a new cable from the modem to the outside where the cable company feeds the house. Bad in-house coax is the responsibility of the home owner. The cable company is only responsible to the side of the house.
 

USAFRet

Titan
Moderator
Mar 16, 2013
147,473
9,354
175,390
23,026
I had pretty much the same issue years ago.
Cable internet/TV.
Internet would cut out for hours, TV would be fine.

3-4-5 times a week.

Call the techs, they send someone out the next day.
All is fine.
Wash rinse repeat.
Eventually ALL equipment from the little interface box in the yard to my PC was replaced. Wiring, modem, etc, etc.

With the Cox modem, one could monitor the S/N ratio of the incoming signal...on their side of the modem.
Kept a log of exactly when it dropped.
It got so where I could predict the internet drop within a few minutes.

At one point, I had 3x Cox trucks and a supervisor out front, trying to diagnose.

Turns out, it was one of their upstream boxes partially dying due to temp/humidity. TV and internet being on different freqs, only the internet was affected.
 

HellboP

Distinguished
Aug 27, 2009
13
0
18,510
0
Simplest thing is to temporarily run a new cable from the modem to the outside where the cable company feeds the house. Bad in-house coax is the responsibility of the home owner. The cable company is only responsible to the side of the house.
Wouldn't it make sense to confirm it's not on their end first, then?

I had pretty much the same issue years ago.
Cable internet/TV.
Internet would cut out for hours, TV would be fine.

3-4-5 times a week.

Call the techs, they send someone out the next day.
All is fine.
Wash rinse repeat.
Eventually ALL equipment from the little interface box in the yard to my PC was replaced. Wiring, modem, etc, etc.

With the Cox modem, one could monitor the S/N ratio of the incoming signal...on their side of the modem.
Kept a log of exactly when it dropped.
It got so where I could predict the internet drop within a few minutes.

At one point, I had 3x Cox trucks and a supervisor out front, trying to diagnose.

Turns out, it was one of their upstream boxes partially dying due to temp/humidity. TV and internet being on different freqs, only the internet was affected.
This sounds like it could be a very real possibility. If that's the case, would their neighbors likely suffer the same interruptions (there are no other carriers here)?
 

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