Connectivity
Connectivity and managing Your Comcast Business network
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20 -30% packet loss at modem DPC3939B

This has been ongoing since the start of Comcast service (2) months.  Average latency at modem 400ms, max 3300ms.

 

Please advise.

 

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Trusted Forum Contributor

Re: 20 -30% packet loss at modem DPC3939B

1) How are you testing this - computer or tablet/phone, wired or wireless?

2) Are you using a separate router along with the DPC? If so, try removing it, connect a computer directly to 1 of the DPCs ethernet ports, and see if the problem persists.

3) Post a screenshot of the modem's downstream & upstream signal levels located at http://10.1.10.1/comcast_network.php

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Trusted Forum Contributor

Re: 20 -30% packet loss at modem DPC3939B

1) How are you testing this - computer or tablet/phone, wired or wireless?

2) Are you using a separate router along with the DPC? If so, try removing it, connect a computer directly to 1 of the DPCs ethernet ports, and see if the problem persists.

3) Post a screenshot of the modem's downstream & upstream signal levels located at http://10.1.10.1/comcast_network.php

View solution in original post

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

TW,

1) via plot, desktop diag. 1a) rj45

2) no separate router, switches by passed for testing, clear.

3) dead link to signal levels, customized?

 

plot:plot redact.png

 

 

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Re: 20 -30% packet loss at modem DPC3939B

yeah sorry sbout that, bad link.

http://10.1.10.1
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Visitor

Re: 20 -30% packet loss at modem DPC3939B

Hey, no problem.  I can get into the modem, not seeing requested data.  Also, that link doesn't work either.

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Re: 20 -30% packet loss at modem DPC3939B

That link should work for you, so it'd odd that is isn't. Anyways, give these a try.  http://192.168.100.1 or http://10.0.0.1 . As for your PingPlotter. The image is very small so I am having trouble reading it. Though, first look doesn't indicate any issues. For packet loss it needs to be carried into the additional hops to present an issue. If the other hops look good(most notably the destination) then you are good. 

 

I just got rid of this modem and I also noticed that for some reason it would not respond to ICMP, even though the firewall was disabled on it. I'm guessing it some time of hardcoded limit in the firmware. 

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

I was told by a field tech that these are suboptimal modems and well hated.   VPN drops all day, all workstations, very third world.

 

Thanks for trying guys.

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Trusted Forum Contributor

Re: 20 -30% packet loss at modem DPC3939B


@dae2 wrote:

Hey, no problem.  I can get into the modem, not seeing requested data.  Also, that link doesn't work either.


You say you CAN get into the modem?

 

If so, then after you login you should see the Gateway "At a Glance" page. From the left-hand-side menu, navigate to "Gateway -> Connection -> WAN Status" page. If you scroll down to the bottom of that WAN Status page, you will see the signal levels.

 

See my attatched pics.dpc1.pngdpc2.png

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

Here you go TW,

 

upanddown.png

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Community Manager
Community Manager

Re: 20 -30% packet loss at modem DPC3939B

Hi dae2. The posted levels are all within range and all channels are locked.  Additionally will you test to IP 68.85.98.130 and post your results and let me know if your PC is using DHCP or your Static IP address.  If your test with a directly connected PC shows latency we can schedule a tech visit to check the coax wiring and replace the device. 

 

Thanks to Kraze & TW for all of the leg work.

 

Thank You

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

Hey John,

 

My workstation and all others (5TL) on DHCP, (2) servers on reservedIP.  Looks like the hop to Pittsburg is without packet loss and max latency of 75ms.  I think the last C tech here experienced a max of 380ms with his laptop, not sure of his test destination.

 

Thanks.

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

Hey John,

 

Went to shut down the trace, saw latency at 406 ms.

 

Thanks

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

Here is the plot.plot 11-13-14.jpg

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Visitor

Re: 20 -30% packet loss at modem DPC3939B

Sooo.... anyone have any ideas about how to keep alive a VPN with 406ms latency? Comcast_John?

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