The content of this blog is my personal opinion only. Although I am an employee - currently of Nvidia, in the past of other companies such as Iagination Technologies, MIPS, Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

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Wednesday, August 26, 2015

Comcast home internet unusably slow (typically afternoons)

Yesterday and today I have worked from home rather than going into the office.

Both days my internet connection has become unusably slow sometime in the afternoon. This has happened before: I used to joke that it happened "When the kids got home from school."  But the kids are still on summer vacation.  Still, it could be "When the kids get off from day camp", or "When the stockbroker down the street stops trading for the day".

This afternoon slowness has happened many times before - so much so that I fell into the habit of driving into the office rather than working from home.  I had forgotten that this was the reason I was not working from home - I was wondering why I was not using my treadmill desk, which I love, as much as I would like (because I prefer to read email in the afternoon on my treadmill desk - and if my Comcast internet is unusably slow, then I try to be in the office in the afternoon, and hence do not use my treadmill desk).

I have not hitherto investigated this problem in detail.  Apart from saying "This is probably bufferbloat", but never getting around to installing modern OpenWRT, with bufferbloat mitigation, on my routers (because my first attempts to install CeroWRT/OpenWRT/DDWRT failed, possibly locked routers).

This blog item to hold notes related to investigating this problem.  In public, because it is unlikely to hurt, may embarrass Comcast into fixing the problem, etc.


Andy "Krazy" Glew said...

dslreports speed test results

This circa 3:20pm, when the slowness starts manifesting.


a) 23Mb/s down, 12Mb/s up
b) Bufferbloat grade B, uploading average 140ms (in yellow "Bad but not terrible" region), with excursions to 210ms

Download speed considerably lower than I have observed at other times (where 100Mb/s and higher is common).

Bufferbloat better than I have observed yesterday and today - at times when the problem was NOT occurring.

This is not inconsistent - if the problem is that the neighborhood shared resources are being saturated, then contention accessing them would result in less bufferbloat.

I suspect that any bufferbloat problem lies on the other side of neighborhood shared resources.

But this may suggest that bufferbloat is not what is making my system unbearably slow.


Andy "Krazy" Glew said...

What a silly idea - using a web based blog to record notes about when internet access is unusably slow. Just posting a comment to this blog takes many minutes.

Better to record offline, and copy online if I really feel impelled to.

Andy "Krazy" Glew said...

Equally silly: it's when my internet access is slowest that I feel most impelled to do research to try to find a solution: like clicking around on Comcast's website to see if there are options, like trying to get OpenWRT to install, etc.

At least I can do such websearches on my cellphone.