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new cisco 3939B and intermittent connectivity

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mecalledjason
New Member

new cisco 3939B and intermittent connectivity

i have a small busniness with a mix of PCs, Apples, smartphones, etc (14 to 16 max at one time). some devices are wired and others are wireless. Comcast switched out our modem about a month ago and we have been experiencing intermittent connectivity. nothing sersious, but annoying and new this has never happened before the switch. i was considering turning the 3939B into a bridge and connect a separate router. however, my wired clients are experiencing the same issue. i was told by comcast support that i should increase my plan to the 50/10 level. i did and now i have highspeed intermittent connectivity. have advice, help?

 

thanks!

Accepted Solution

Re: new cisco 3939B and intermittent connectivity

issued solved.

i called tech support explained my issue. the technician could tell i was having intermittent connection issues. however, instead of changing my LAN/WAN DNS settings over the phone he scheduled for a tech to come on site that afternoon.

 

the technician on site ran a few tests that resulted in the following:

  1. the 3939B was being identified by comcast as only a 'standard' modem.
  2. the signal coming into the modem was off the charts; way too much signal.

 

the tech solution:

  1. called the denver office incharge of all busniess traffic to register the modem correctly
  2. callibrated the modem to handle the signal by connecting a splitter to step-down the signal. seemed like a mcgyver-type solution to me, but it seemed to work.
View solution in context
Trusted Forum Contributor

Re: new cisco 3939B and intermittent connectivity

Hello mecalledjason and welcome,

 

I recommend that you call 8003913000 and use the technical option. Ask the technical agent to log into your DPC3939B and set the following:

1. WAN DNSs to 75.75.75.75 and 75.75.76.76

2. LAN DNSs to 75.75.75.75 and 75.76.76.76
3. Leasetime=FOREVER
4. request that your downstream and upstream power levels be examined and are within specification.

 

The above settings will provide consistent functional internet operation and insure that your devices connected to the internet will never loose their dynamic IP addresses.

 

Hope this helps you out.

mecalledjason
New Member

Re: new cisco 3939B and intermittent connectivity

thanks VBSSP-RICH, i will keep you (and anyone else) informed to the results.
mecalledjason
New Member

Re: new cisco 3939B and intermittent connectivity

issued solved.

i called tech support explained my issue. the technician could tell i was having intermittent connection issues. however, instead of changing my LAN/WAN DNS settings over the phone he scheduled for a tech to come on site that afternoon.

 

the technician on site ran a few tests that resulted in the following:

  1. the 3939B was being identified by comcast as only a 'standard' modem.
  2. the signal coming into the modem was off the charts; way too much signal.

 

the tech solution:

  1. called the denver office incharge of all busniess traffic to register the modem correctly
  2. callibrated the modem to handle the signal by connecting a splitter to step-down the signal. seemed like a mcgyver-type solution to me, but it seemed to work.
Community Manager
Community Manager

Re: new cisco 3939B and intermittent connectivity

Hello mecalledjason,

 

Thank you for the follow up post, I'm glad to hear your issue has been solved.

 

Please let us know if any issues come up.