LAN is given wrong Default Gateway by my AT&T router

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LAN is given wrong Default Gateway by my AT&T router

The address of my AT&T router is 192.168.1.254.  About once a week this router pushes out the wrong gateway of 192.168.1.1.  At which time I am unable to access the internet.

 

The wrong gateway gets assigned when I use DHCP.  If I have a static IP address assigned, I get a second Default Gateway of 192.168.1.1 which also prevents me from accessing the internet.

 

Sometime I can Ipconfig /release, then Ipconfig /flushdns, and Ipconfig /renew.  About 50% of the time this solves the problem.  The rest of the time I can't get rid of the 192.168.1.1 gateway for hours at a time.

 

This happens on both wired and wireless connections.

 

This occurs randomly on every device in the house trying to connect to the internet: Desktop PC (wired), Laptop (wireless), Iphone (wireless)...

 

I have AT&T support for help.  Spoke to level 1 with no help.  When I asked to speak to level 2, they sent a technician to my house.  He replaced the AT&T router.  I still get the same problems.

 

I do NOT have any addtional routers attached.  I do have one 8 port Cisco switch and one Netgear 8 port switch (provided by AT&T) on the network.

 

How can I prevent this problem from continually messing up my internet connection?  I am about ready to switch to Time Warner cable.

Message 1 of 8 (3,486 Views)
ACE - Master

Re: LAN is given wrong Default Gateway by my AT&T router

[ Edited ]

It sounds like you have a rogue device somewhere on your network sending out DHCP.  From your post the only thing I can think of would be the Cisco Switch.  The Netgear AT&T supplies won't do that.  Does the Cisco have the ability to do DHCP?

 

There is no way I know of to change the AT&T router to give out a different Gateway.  What happens if you type in 192.168.1.1 in your browser?  Does it bring up anything?  Can you ping it?  If you can something is on your network with that IP.  Try disconnecting the Cisco and see if the ping returns a no reply.  Go thru your devices until you find the offending one.

 

One other thing.....you don't have Internet Connection Sharing turned on on any of your computers do you? 

http://windows.microsoft.com/en-US/windows-vista/Using-ICS-Internet-Connection-Sharing

    

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*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 2 of 8 (3,472 Views)
ACE - Expert

Re: LAN is given wrong Default Gateway by my AT&T router

haysk1 - The next time it appears - put the ip address in your browser & access the GUI. When it asks for credentials, leave the first box blank & enter admin in the second. This is the default for LInksys & may let you in.
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 3 of 8 (3,464 Views)
ACE - Master

Re: LAN is given wrong Default Gateway by my AT&T router

What Linksys?  I didn't see a mention of a Linksys in the post.  Do you mean Cisco?

"If you find this post helpful and it solved your issue please mark it as a solution.  This will help other forum members locate it and will also let everyone know that it corrected your problem. If they have the same issue they will know how to solve theirs"

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 4 of 8 (3,463 Views)
ACE - Expert

Re: LAN is given wrong Default Gateway by my AT&T router

No, I have a linksys that works as I described. Also, linksys is same as cisco. Probably will not be a successful effort. Just offering something to try to learn what is going on.
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 5 of 8 (3,459 Views)
Tutor

Re: LAN is given wrong Default Gateway by my AT&T router

My Cisco is a Cisco Pix 501 Firewall.  I was using it as a simple switch.  I tried going to http://192.168.1.1 but the page would not load.  I have taken the 501 out of the network.  Now if I ping -a 192.168.1.1 it resolves to my desktop ip address with no response.

    I will keep the 501 off of the Network for a while and see if it was the culprit.

Message 6 of 8 (3,439 Views)
Tutor

Re: LAN is given wrong Default Gateway by my AT&T router

   My Cisco is a Cisco Pix 501 Firewall.  I was using it as a simple switch.  I tried going to http://192.168.1.1 but the page would not load.  I have taken the 501 out of the network.  Now if I ping -a 192.168.1.1 it resolves to my desktop ip address with no response.

    I will keep the 501 off of the Network for a while and see if it was the culprit.

Message 7 of 8 (3,439 Views)
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ACE - Master
Solution
Accepted by topic author haysk1
‎09-30-2015 1:39 AM

Re: LAN is given wrong Default Gateway by my AT&T router

I suspect that it is the Cisco causing your issues.  You access it by doing this: To access the Startup Wizard, use a PC connected to one of the PIX Firewall switch ports and enter the URL https://192.168.1.1/startup.html into your browser.  Of course your computer would need to be on the 192.168.1.?? network (which it should already be) and plugged directly into the Cisco on of the ports 1 thru 4.  You should at that point be able to see the start up screen.  I didn't dig very deep but you should be able to turn off DHCP in the set up.

 

Here is a link to the manual I looked at: http://www.cisco.com/en/US/docs/security/pix/pix63/quick/guide/63_501qk.html

 

 

"If you find this post helpful and it solved your issue please mark it as a solution.  This will help other forum members locate it and will also let everyone know that it corrected your problem. If they have the same issue they will know how to solve theirs"

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 8 of 8 (3,434 Views)