Why intermittent Internet activity with modem/router setup

pbo1
pbo1 used Ask the Experts™
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I have broadband cable internet with Comcast via a Linksys Cable Modem and a Linksysy E2000 router.  

Problem:  2-3 times an hour my internet activity goes out for several minutes.  One desktop is connected to the router via ethernet and 1 laptop is connected to router via wireless.  When the internet connection returns (usually a few minutes) the speed is excellent.  If I try to bypass the router (plug the PC directly into the Cable modem) I am unable to get an Internet connection even when  the Internet connection is back up.

Comcast has been out and provided a new splitter and a new line from the telephone pole to my house.  Comcast will come back out, but I am wondering what troubleshooting steps I can take prior to there arrival.  Also, what tool can I buy to measure the speed of my connection where the internet comes into the house and the splitter starts..
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Dave BaldwinFixer of Problems
Most Valuable Expert 2014

Commented:
I don't know whether Comcast does it but some ISPs require the right MAC address from the ethernet connection in order to connect.  Your PC won't have the same MAC address as the router.

You can't measure the internet speed before the cable modem because the modem is what converts it from the cable format to a network format.  Before that, it's just one of many signals on the wire.

Comcast is a party line with many people sharing the path.  I'm wondering if they are doing some bandwidth throttling on your branch of the cable system.  Or maybe your section just gets overloaded because of too many users.

I believe it is possible for them to monitor and measure the signal quality at your place.  Ask if they will do that next time.
Commented:
I have seen this happen a few times. It always turned out to be a bad cable modem. try replacing it.
If you bypass the router, did you power cycle the modem and renew your IP on the hardwired PC?

What does IPCONFIG /ALL show?


Are you on the latest firmware for the router?
http://homesupport.cisco.com/en-us/wireless/linksys/E2000/download


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Also, what OS are you using?   When you are having an outage, persistently ping something like google...

ping -t  www.google.com

Are you getting any time responses, "generic failure" messages, etc?

My wife has a Vista laptop and for the longest time, we were having what appeared to be random outages.  On her wireless laptop and on the hardwired computers.   During the outage, I could still ping google, but would see "generic failure" pop up every so often during the pings.

It turned out that Vista and its IPV6 settings were causing the outages - didn't play nice with the Router.   Ever since I disabled IPV6 AND disabled the "IP Helper" service, not a single outage in over a year.




Author

Commented:
I Have Windows 7 and will try some of the suggestions when I get home.  I also noticed ipv6..What is ipv6 ?  is it ok to disable ?
Since IP address spaces are running out, the newer IPV6 attempts to address that.  IPV4 is 32bit whereas IPV6 is 128bits long.   It is okay to disable for the foreseeable future.  You can turn it on down the road if you ever need to.

Author

Commented:
I tried pinging and did not find any issues along with a few other suggestions found above, but nothing worked.  I replaced the modem and router with a Motorola Surfboard SGB6580 and I have been running a full day without any issues..thx

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