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kucharsk
join:2001-03-30
Louisville, CO

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Re: [Speed] Speeds all over the place since 100 upgrade; anyone

Yeah… the problem continues here.



AnonMan
@comcast.net

AnonMan

Anon

This isn't always going to be the speed test servers like you all think.

At the moment the cable plants only support 8 DS channels. So around 300Mbps of service.

If your node just happens to have a good deal of people on it this is the result of the shared bandwidth hitting its limit... The node could have a 1Gbps link but does no good since the coax is limited with the 8 channels currently used.

My area doesn't have many Comcast users as most are on Bright House so my speeds are great but if you have a few others with the high speed package or even just a bunch with the lower ones it adds up...

The Comcast test servers are generally on the 10Gbps backbone link so doubt it's a speed issue with them and is likely local...

Best I can suggest is make sure you have an 8 channel DS modem if you happen to only have a 4DS channel Docis 3 one and that will help solve your issue for the moment.

Docis 3.1 will solve the issue when it's rolled out next year but you got a while for that and even after that the issue can re-appear if the speeds are kept updated like this.
gr82cu
join:2013-04-08
Dickson, TN

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I personally never use the CC speed test site in the first place. It has been wildly inaccurate for me in the past. All of them have their downside but I have had the best luck with testmy.net .
kucharsk
join:2001-03-30
Louisville, CO

kucharsk

Member

I use the CC speed tests as they're the only one (in my experience) Comcast Support considers "official."

How many channels does an SB6120 support? That's what I have.
rody_44
Premium Member
join:2004-02-20
Quakertown, PA

rody_44

Premium Member

Try another speed test. Or better yet a real world download. Speedtests are not very accurate when you get up to 100 Mbps speed.

C_Chipperson
Monster Rain
Premium Member
join:2009-01-17
00000

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said by kucharsk:

I use the CC speed tests as they're the only one (in my experience) Comcast Support considers "official."

How many channels does an SB6120 support? That's what I have.

I was on the same modem, it supports 4 downstream and 4 upstream channels. I bought a Zoom 5341J 8x4 modem a couple weeks ago after the speed upgrade, and I consistently see ~115-120mbps down and ~20mbps up. With the SB6120 it would vary quite a bit. So I think having the additional downstream channels on the Zoom modem helps stabilize the speed.

Edit, here is a speed test I did with my 5341J (Over WiFi believe it or not!)



And a test with my SB6120 a few weeks ago, but same time of day for comparison:


AnonMan
@comcast.net

AnonMan

Anon

Sounds like indeed the channel issue.

Get a new 8DS channel modem and I bet your issue is gone for the time, unless too many in your area upgrade speeds lol.

I personally have the Cisco DPC3008 and love it. Had issues few years back but been great after fw fixes. Others like zoom, just get whatever you can get a good price on. Almost every 8 channel modem uses the same internals for the most part. I think only 2 chipsets exist for them so the rest is just layout changes and firmware.

As for speedtests sites, it depends on location really. If you have a Comcast one near you the speeds should be more accurate vs. any others as all data would be on net, but if it's a bit far it might not be accurate. I have 3 Comcast ones on net near me all under 15ms and all on 10GB back links and all accurate. some of the speedtest.net ones are owned by ISPs also fwiw. Other tests sites the accuracy depends on load as even if they are on 10GB back link they require you to travel through other links to get to them that might have load vs. if a local Comcast one it would be local on net and not travel far thus risk of load lower.