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Bealeton, VA

[Connectivity] Comcast packet loss

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Basically my connection is totally unstable. I am getting constant lag spikes and packet loss. The happens no matter what device I am on, wired or wireless, connected to a router, or directly connected to the modem. I noticed the issue first back in Dec for a few weeks on and off, then it was fine for about 1 1/2 weeks, now it's back.

I have tried calling Comcast support and have gotten the usual; reboot your modem, PC etc with no resolution. I am trying to avoid having to take a day off from if at all possible for a Tech visit, or at least understand the problem a little better.

1.Location: Bealeton, VA

2.Description: Packet loss/lag spikes

3. Issue is "consistently" intermittent. Happens at all times of the day, sometimes it will get worse for a while, sometimes it will be ok for 10-15 minutes.

4.Hardware: Motorola Corporation sb5120
Software Version: SB5120-
Hardware Version: 4
MIB Version: II
GUI Version: 1.0
VxWorks Version: 5.4

5.Other hardware: Netgear n600 router/WNDR3400 (though issue still is there even if this is eliminated from the connection)

6.Anti-Virus/Firewall- MS Security Essentials

7. Default Gateway (I think??):

8. Signal Levels- Attached

9. Ping Plotter results- Attached (hopefully the right way)

10. Smokeping/Line Packet Loss Testing: *I noticed that I couldn't become "pingable" from either the Ping Test or Smokeping. I tired following the directions to become pingable through Win7, but had not luck. Not sure if this is due to the router blocking something or not. I will connect directly to the modem and try again if asked/needed.

Hopefully I have included at least the basic information necessary. Has anyone else been experiencing this problem recently? Any ideas?

Quakertown, PA

Someone else will come along with more knowledge but im sure it would be better without the router since it looks like its out of the router.


Bealeton, VA

That's what I was hoping, but I still get the loss regardless if I am going through the router or directly to the modem. I tried tests with 2 different laptops in various configuration- behind the router, wireless connection, wired connection, and eliminating the router altogether and testing directly from the modem.


Stuarts Draft, VA
reply to BigPappyJapp

Have you thought about buying a new modem ?

Not have a D3 modem isn't helping you any. I'm not saving it will 100% solve your problem but it certainly wouldn't hurt you any.


Bealeton, VA

No, but it's worth a shot. Thanks!

Snohomish, WA
reply to BigPappyJapp

You could try renting a D3 modem from CC for a month or 2 just to see if it helps.


Bealeton, VA

Thanks for the heads up. I remember last time I was in the local office someone was asking for them and they said that they were out of them for the moment.

If I were to purchase one, I'm guessing this would be what you guys are talking about:

I saw a few others on Amazon, an "Extreme" version, and one that was an Modem/Wireless router, both from Motorola. Those any good, or just stick with the basic one?


Washington, NJ
·Verizon Online DSL

I'd recommend this:


Same price, later model...
"When will they ever learn? When will they ever learn?"
Pete Seeger 1961


Stuarts Draft, VA

Wouldn't recommend buying from a reseller on Amazon...

·AT&T U-Verse

2 edits

The retail model for the SB6141 is:(Available from Amazon directly)
SB6141 from Best Buy for same price:(If you don't want to deal with shipping)

Kind of expensive though.

Modem that is often recommended by people on this forum:(Only available from non Amazon sellers)

Too bad the DPC3008 isn't $69.99 on Amazon anymore. I got it during that time and it's been great so far. Hasn't dropped out yet and runs pretty cool(I stand it up on the side and usually only the top is warm, the sides are slightly cool)but, I really hate how the information page doesn't give you that much information about your channels.
DPC3008:(Available from Amazon if you click on them)

Most people suggest that you make sure you buy directly from Amazon when using Amazon though when buying modems.

Ukiah, CA
reply to BigPappyJapp

Best Buy should have the Zoom 5341J in stock if you would rather go to a brick and mortar store. The last time I went to one (November), they had the Zoom and I think a Motorola SB6121. The Wal-Mart in my town had the SB6121 as well, although for a fair amount more than newer modems elsewhere.

reply to BigPappyJapp

said by BigPappyJapp:

If I were to purchase one, I'm guessing this would be what you guys are talking about [...] I saw a few others on Amazon, ...

Don't see it mentioned here yet so be aware Comcast has an Approved Modem List --

Someone correct me if untrue but it's my understanding Comcast maintains customized firmware only for the listed makes/models and will not allow others onto their network.

In Nov.2011 I bought a used Ubee DDM-3513 from a Craig's List seller for $55 and have placed it onto three different Comcast accounts since. Been very stable.

Good luck! Let us know what route you took.