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Lovemylab's avatar
Lovemylab
Contributor III
2 years ago

Looking for internet/network insight

I had an unusual experience yesterday and I'm hoping one of you can help me gain insight.

My wife said she was having internet issues so I immediately power cycled "everything". Modem, router, switches, etc. on a switched surge protector.

When everything came back up, the Arris Modem connection looked good as did the event log. However, I couldn't connect to Cox via internet to see if there was an outage. My wife could not connect to her work. However, I could connect to Gmail, send a Gmail to Outlook, open Outlook via web, and could successfully perform Google searches.

So, I thought, perhaps there is a DNS issue going on. I tried to ping 8.8.8.8 and it timed out. I tried to tracert to 8.8.8.8 and never got a response back from my Google router. So, I concluded that perhaps my router had failed, or perhaps Google was having an issue (config is managed in the cloud) so needed a work around. I then grabbed my wife's laptop and connected it to the back of the modem and rebooted the modem. I figured if I could establish a connection that way I could jury rig a connection to her office while I addressed the router. Everything came up, I could ping 8.8.8.8, I could tracert. So, I figured I'd take a minute and swap back to the router just to confirm. Rebooted, and everything went back to working just fine.  I told my wife she could go back to work, and reached out to Google to see if they could provide an explanation. They did a little research and said they had no sign of issues and my network looked good from there end (I had to enable access).

So, any thoughts? The behavior suggests something like bad cached DNS, but I would have expected a power cycle to correct that. I'm trying to understand what might have occurred so I can be more proactive going forward. Then again, I've never seen this before.

  • My guess is it had something to do with IPv4 vs IPv6 traffic. You were getting one, probably IPv6, but not the other. Check your IPv4 and IPv6 WAN IP of the google router next time you have a issue. Also ping a IPv6 address like Facebook.com.

  • WiderMouthOpen's avatar
    WiderMouthOpen
    Esteemed Contributor

    My guess is it had something to do with IPv4 vs IPv6 traffic. You were getting one, probably IPv6, but not the other. Check your IPv4 and IPv6 WAN IP of the google router next time you have a issue. Also ping a IPv6 address like Facebook.com.

  • OSI reference model is your friend, link below:

    https://www.cloudflare.com/learning/ddos/glossary/open-systems-interconnection-model-osi/

    Your theory seems to be DNS issue but let's analyze that further.  When the problem occurred, you said you tried to ping 8.8.8.8 when the router was connected but it timed out.  Pinging by IP address failing confirms that DNS Is not a factor.  Doing a post mortum analysis of your reported symptoms, I would suggest your problem lied somewher in the communication between layers 2 and 3 of said model posted above.

    Most likely, either frames weren't passing correctly at layer 2, or TCP/IP packets weren't passing at layer 3. These symptoms would suggest I look for a software issue as it applies to hardware.  Think network drivers or network hardware firmware/software.

  • Darkatt's avatar
    Darkatt
    Honored Contributor

    My first thought, make sure the router is powered off until the modem is online, then power up the router and then all the equipment after it. that includes all computers/tvs/tablets/cell phoines etc etc to ensure there is no errors like a duplicate ip address. 

  • Lovemylab's avatar
    Lovemylab
    Contributor III

    Thanks for all the input. Based on the fact that I had connectivity to a certain set of external sites, but not others, I'm leaning towards the thought that there was a temporary issue, for an unknown reason, with IPv4. It would help if I could remember for certain whether Amazon worked or not. Google, Facebook, Microsoft365 are all IPv6 compatible. Amazon, Cox, and the corporate site my wife needed are not. If this ever happens again, I have a better model for analyzing the issue.