[PLUG-TALK] Comcast intermittent woes

Paul Heinlein heinlein at madboa.com
Sat Oct 28 14:04:50 PDT 2017

Short version: Rock solid until two months ago, our Comcast internet
(but not TV) connection goes down for long periods of time every
few days. Only known solution is to disconnect cable physically and
completely from "modem" for several minutes.

Long version:

We moved into our current home nearly five years ago. We've had
Comcast internet and basic cable TV since moving in. Connections were
solid and reliable until early September. Outages were few and far
between, and usually lasted no more than two hours.

Starting in early September, we started experiencing multi-hour
outages, sometimes lasting more than a calendar day. Occasionally,
power-cycling the Comcast-provided modem would do the trick, but often
not. Outage lengths became unpredictable.

Two things worth noting. First, as far as I'm aware, we made no 
changes to the physical environment that would impact any cable run. 
Second, none of the outages to this point or any that followed 
impacted our ability to receive a television signal over our cable 
connection. Only internet is impacted.

Suspecting power problems, I took the two UPS units into which my
computer and networking gear are plugged down to Batteries+. One
battery was fine; the other was on its last legs, so I replaced it.
I also took that opportunity to remove all gear and furnishings
from the study to do a deep cleaning. After cleaning, service was

Then, more outages. Like those before and all subsequent ones,
television connection was fine; only Internet was impacted.

During one outage, I called customer service. The very articulate guy
on the phone walked me through an entire power drain of the modem, a
procedure that included removing the internal backup battery. I
suspect I disconnected the cable during that procedure, but I can't
remember. He stayed on the phone with me as we waited a couple minutes
before connecting everything. Service was restored.

Then, more outages...

I scheduled a tech to come out. He noted that my modem was deprecated,
so he installed a new one. At my request, he turned off its native
wifi and configured it in bridging mode. Service was restored.

Then, more outages...

Tech #2 came out a couple weeks later. My wife was here; I was at
work. I'm not sure exactly what he did, but service was restored.

Then, more outages...

Tech #3 came out and ran a new drop from the utility pole to the
house. He also removed an older splitter from the cable run in the
house. Service was restored.

Then, more outages...

Early last week, I followed the cable run into a crawl space and
swapped out yet another splitter. Service was restored.

Then, another outage this morning. This time, I just unplugged the
modem and disconnected the cable for three or four minutes. Service
was restored.

As far as I can tell, the only surefire way to restore service is
to disconnect the modem from the cable. The same appeared to be
true with our old modem, so I do not suspect a faulty unit.

Has anyone seen this before, where cable disconnection solves the
problem? Is there a decent fix?

Paul Heinlein
heinlein at madboa.com
45°38' N, 122°6' W

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