Home Networking

I work at an ISP and we have guys doing this constantly. It's not always at a customers house but yeah. A fault on the cable going to your house causes your modem to increase the power it uses to talk to the node in your neighborhood that connects back to the ISP. If your modem uses too much power and drowns out the signals from your neighbors going to the same node, then everyone else's service can suffer and yours is just fine. It's weird but that's how it is.

A connector might have gotten rusted or a landscaper might have nicked a cable with a weed Wacker or something.

Uncapped outlets can cause backfeeding, as can damaged cables; when I worked in the field a factory had a damaged coax feed and when one of their machines started up it would knock out the leg. Coax is basically a wireless signal that is stuck on the antenna (wire) rather than a digital signal like Ethernet, and it is a shared medium unlike DSL.

This is 90% of my job every day. Something in your house is acting like an antenna and interfering with the return path. Most of the time it’s a loose connector behind the modem but any bad connection can cause it. I usually track the noise to a house and use a filter at the tap that blocks the noise and leaves the sub online, then create a job to get an tech in the house

Man, coax goes berserk when the shield breaks down. A good example is CCTV, some buffoon at my old work thought it would be smart to order copper shielded coax, and use steel crimp ends in a tropical area. It was a few years but the moisture caused electrolysis between the dissimilar metals, and the copper shield disintegrated. In the space of around 6 months the CCTV feeds started to fail. It was fun replacing all of the coax with fibre.

Totally normal. They detected egress and needed to correct it.

Yes. This is true for coax. Due to how coax is wired, every signal goes to every house, just like tv goes to all the houses on the circuit. It’s up to the coax equipment to filter out the signals that aren’t for that connection (just like a cable box is programmed to only allow the channels you pay for).

But the issue is, if a cable isn’t terminated correctly, it looks exactly like an antenna. This will cause noise on the whole coax system and affect everyone on the same circuit.

Do you have an antenna on your system or a distribution box?

Would amplifiers like the Motorola Cable amplifier cause something like this? Also, what about not using termination caps on non used connections? Answer me!!!!!!

If you have any MoCA adapters and you don’t have a filter on your house.. you might be sending that info out over the wire. I had that happen once.. using MoCA adapters. Cable guy calls me and says I am putting out “stuff” into the system. I happened to be on vacation at the time.. told him I would be back next week.. I added an adapter inside my attic before the coax went out to the neighborhood and asked them to check again.. they never responded and never came back.

Then years later (maybe 1 year ago) when a guy came over to re-run my line out to the box (I think neighbors lawn people cut it).. he slapped a MoCA filter into the connection box and said they were standard/required now. So I was able to remove the one in the attic.

You have a bad splitter. Let them in.

Welcome to the world of Coax and why I'm so damn glad I got fiber now.

Same thing happened to me,
But the noise was intermittent 2 minutes every 10 or so. It was upstream channels, so tech suspected it was someones modem failing.

No way to find out who's modem without shutting them down in groups in process of elimnation.

Took about 2 days and my upload was eventually returned from 100k back to 10mb

I heard a story from a guy who worked maintenance for Comcast in the Seattle area about a bizarre fix for this kind of thing. They had a neighborhood that was doing offline everyday at the same time, like from 8-10 pm, everyday like clockwork and they couldn't get a fix on the cause. So they finally got a couple nightshift guys in bucket trucks to sit in the neighborhood and, using online tools to monitor the node, watch for the noise to kick in. One guy was sitting in front of a house and right about 8, he notices a person in the house sit down in front of a window and turn on a light. Instantly he starts seeing noise in the node. On a hunch he went and knocked on the door, explained what was happening and asked the customer if they could indulge him and just go turn that light off ta few minutes. They do, and the nose goes away. The customer let him in to investigate and it turned out it was an antique lamp with a fraying old fabric wrapped power cord, plugged in to the same outlet that the modem was plugged into. So somehow this lamp was feeding voltage or low frequency noise into the outlet and the modem was picking it up through its power cord and feeding it back into the system. The customer said it was his nightly before bed routine to sit in that chair under that lamp and read a book. They had to ask the customer to please not use that lamp, or get it repaired, or move the plug for the modem to another outlet He said it was one of the more bizarre coincidences that they were able to just witness the cause. If they hadn't seen it, it might have taken a few days of nightly monitoring to chase the nose down to that one particular house in the 2 hours it was happening everynight.

I had this happen a few months ago. They weren't nice enough to call, they just trapped my line and shut off my internet for up to 2 days while I had to wait for a tech to come.

First time they needed to replace the line from the box to the house. After that they couldn't find what was wrong but they shut it off like 2 more times :(

I've previously reported an issue to my ISP and it turned out to be loose cables and unterminated cables. Once that was taken care of all was well again. So now every once in a while I check the tightness. I find it amazing they can even loosen up, but they do just from minor jostling of boxes.

Has this happen as well, of the wire acting as an antenna is bad enough, the ISP may even get a letter from the FCC from my understanding. In addition to replacing every connector, they disconnected all unused coax connections or made sure unconnected points had grounded caps on them.