Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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Frequently Rebooting Modem

We have a leased SMC Networks SMCD3G-CCR modem that is almost 4 years old.  Recently we have been experiencing intermittent connectivity issues.  During this time our ping time will go thru the roof (can be well over 100ms), the speeds drop to a crawl, and users will report programs showing they are disconnected.  After power cycling the modem things go back to normal operation – ping times under 20ms, speeds at or slightly above our package rating.  We’ve been needing to power cycle the modem more and more frequently, this is now occurring more than once a week.  Do we need to get this modem replaced? Or is there something else causing this issue?

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Re: Frequently Rebooting Modem

Hello ecandsinc and welcome,

 

Could you please run through this troubleshooting process  to determine if you need to have a Comcast technician dispatched to your location for resolution.

 

Hope this helps you out,

 

 

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Re: Frequently Rebooting Modem

I ran throiugh the guide you linked to, and here's some comments from the suggestions in each section.

 

Check your modem signal levels

Levels look reasonable, Downstream power between +4.5 and +5.5 on 4 channels, SNR between 37 and 39, upstream power 48.0 and 46.5.  These numbers were from the modem during normal operation. The numbers during a time with connection issues were virtually identical.

 

Check that your modem is not EOL (End of Life)

Modem is not EOL, it is SMC Network SMCD3G-CCR, DOCSIS 3 modem as noted earlier.

 

Power-cycle all equipment

Power cycling modem corrects problem as noted in the original post. The problem returns within a few days.  We have a static IP, so I am not doing a hard reset.

 

Inspect coaxial lines and splitters

Coax line coming into IT closet looks good. No noticeable damage. No splitters in the line at this location. We are one of many tenants in the building, I'm not sure of where the coax line enters the building or if there are splitters between the building entrance and our IT closet.

 

Routers

We are running in partial bridge mode with a third party firewall. Directly connecitng a laptop to the modem (bypassing the firewall) shows the same problems when this issue is happening.

 

For DHCP and static IP Users

We have been using google's DNS. We’ve been using their DNS long before this problem began.

 

Check your speed

As noted originally, the speed will be fine for a few days - at or slightly above the rated connection speeds with good ping times. Every few days the speed on a speed test will drop substantially. Lag times can go up by nearly a factor of 10. Multiple users will complain about connectivity errors in email and other programs.  Some programs have timeout errors.  Power cycling the modem quickly puts everything back to normal.  This used to be a once in a while issue, then about a once a week issue. This morning was the third time this week I had to power cycle the modem.

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Re: Frequently Rebooting Modem

If swapping the power adapter does not fix it the modem is probably toast,

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