Possible DNS issue - Having trouble diagnosing the source of my connection problems

element6

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Aug 30, 2014
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Ever since I've moved in to my current home, I have been having strange connectivity issues with most devices on my home network. The issues are intermittent but primarily noticeable when browsing.

My ISP is Atlantic Broadband (Unleashed 120/10Mbps) and my network currently consists of the following:

  • Motorola/Arris CM820
    ASUS RT-AC87U plugged into the above cable modem. No other devices plugged in. Set as Parent AP (Media Bridge)
    ASUS RT-AC87U connected to parent AP across the 5Ghz band. This router is in Media Bridge mode and the link rate always shows an even 1170Mbps or so. Any wired clients on my network are plugged into the LAN ports of this router.
    Netgear GS116 Gigabit switch plugged into port 1 of the RT-AC87U above.

On the main router that is plugged in to the cable modem (where I make any changes to my network settings), the 2.4Ghz and 5Ghz bands are both enabled for the wireless network in my home. However, because the media bridge link is going across the 5Ghz band, I disabled advertising the SSID for the 5Ghz wireless network so nothing would connect to it. All wireless clients use the 2.4Ghz band. I have no problems with connectivity either with my media bridge or with clients on the 2.4Ghz network.

Why am I using a Media Bridge?
I am renting and the only place that the coax could come in to the apartment was in the kitchen above the cabinets by my refrigerator. There is no easy way to bring coax further in to the apartment so that I could have only one router for all my wired equipment.


What is the problem?
When I have issues, all clients on my network are affected. Wired and wireless.
It is most easily detectable when I am browsing because I can no longer reload any pages or navigate to new web pages. Browsers will sit there trying to resolve the server until they timeout.
It occurs with any browser. IE, Chrome, Firefox, Safari Mobile, you name it. Does not seem browser related at all.

If I am using my laptop (Windows 7) on the wireless network when one of these events occurs, I can open a command prompt and try to do "ping -t google.com" and all I will get is "Reply from 192.168.1.1: Destination host unreachable" until the problem clears itself up. I get the same exact output if I use my Windows 7 desktop when an issue like this arises.

This all leads me to believe that it's either a problem with my router configuration or a problem with my modem.

My modem does not show any changes in it's connectivity during this time and I can access the router configuration page from any client when the issue comes up. While it is occurring, the router says that there is still an internet connection.

Can anyone suggest what I can do to further troubleshoot these issues?
 
Solution
You likely do not have a DNS problem.

That message has a very specific meaning. It means your packet got to the router but the router does not know where to send it. It has no route to the destination in its routing table. For a home router pretty much this always means your internet connection is down.

If it were a DNS error you would get a unresolved message but if you were to ping the actual IP address it would respond.

I am not real sure how it would know the ip of google.com and then send the data but it may have been cached someplace either in your router or in your PC.

I generally leave a constant ping run on one of my machines to 8.8.8.8 and to the first ISP router in the tracert. When I have problems I can then...

element6

Reputable
Aug 30, 2014
13
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4,510
Thank you, but I have tried manually setting my router to use Google's public DNS servers with the same results occurring just as frequently.

The one thing I have done within the last month that has seemed to make some issues a little less frequent was disabling IPv6 on the NIC's of my laptop and desktop.
 
You likely do not have a DNS problem.

That message has a very specific meaning. It means your packet got to the router but the router does not know where to send it. It has no route to the destination in its routing table. For a home router pretty much this always means your internet connection is down.

If it were a DNS error you would get a unresolved message but if you were to ping the actual IP address it would respond.

I am not real sure how it would know the ip of google.com and then send the data but it may have been cached someplace either in your router or in your PC.

I generally leave a constant ping run on one of my machines to 8.8.8.8 and to the first ISP router in the tracert. When I have problems I can then quickly see what if anything looks down.
 
Solution