Router/modem question

Question:  Having some intermittent internet connectivity issues.   I have a dsl router/modem connected to my internal network.  I have a switch with several computers connected.  Two servers connected to my switch.  Ethernet cable running from dsl modem/router to the switch.  All has worked well for several years.  When I do a diagnostic on the router, it fails the gateway and dns part of the test.  What does that mean?

I have my domain controller pointing to the router - the router is the gateway out to the internet.  If the router is failing the gateway test does this mean the router is bad?
The router is only routing out to the internet.  No dhcp or dns.  My domain controller (windows 2003 server) is doing all of that.
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Rob HutchinsonTech Lead, Desktop SupportCommented:
Assuming that the DSL modem came from your ISP, did you contact your ISP to see if they DSL modem's internet IP address changed? Did you have a static IP before assigned on the DSL modem internet interface?

I'd also check the inside interface of the DSL modem to make sure that the gateway/dns your server thinks is the right gateway/dns--is actually programmed on the DSL router inside interface.
manch03Author Commented:
I did contact ATT and have the correct ip address.  I did assign a private ip address to the router and have that 20. ip address  that I assigned to the modem/router in my server as the gateway.  

The router has a 172. address from ATT.   I have the 20. ip address as my gateway in the static ip address of the server.  I do have the dns server ip address defined in the router's interface.
Rob HutchinsonTech Lead, Desktop SupportCommented:
One thing that you should do, is make it simple by taking one computer attached to the DSL router and see if you can get out using that one computer...maybe even get your ISP to help you so you are using the correct IP addresses on both sides of the DSL modem for just this one computer...forgetting about the server for the moment.

Once you have that one computer working on the internet...leave that computer's config alone, then config the server to be have similar setting and trying to just get the server out on the internet like the computer.

Once you have the server back on the internet, try an get another computer out from one of the other computers attached to the switch.

If you can get those computers out then you should be good.
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manch03Author Commented:
Here are some screen shots of my ipconfig on the domain server and the screen shots for the settings for dhcp and dns on the router/modem.
Rob HutchinsonTech Lead, Desktop SupportCommented:
If you cannot get anywhere using what you know to be the correct config for the DSL modem and a single computer, then maybe your DSL modem isn't working correctly and you can get another DSL modem.

Most stores offer at least a 10 day return policy so try an get a replacement DSL modem to work with a single computer like I just described. If the single computer works with the new DSL modem, then your problem is solved and you just need to get everything hooked back up.

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manch03Author Commented:
I can attach a laptop directly to the router/modem and get out to the internet.  Everything works for a while - 3 to 4 hours and then the internet connectivity starts to lag and eventually stops working.  I unplug the router/modem and everything works again.  But I don't think I have this set up correctly.
Rob HutchinsonTech Lead, Desktop SupportCommented:
dns - att told me to leave

hmm, not sure I agree with that one as adding DNS here which is from your ISP is not going to hurt anything.

regardless, this shouldn't prevent you from pinging the gateway from the server or one of the computers.

Is your problem with name resolution or are you unable to ping the gateway from another computer?
manch03Author Commented:
Here is the main screen on the modem/router.
manch03Author Commented:
When I do a self test on the router, it fails on the gateway and the dns part.  I will send a screen shot.
Rob HutchinsonTech Lead, Desktop SupportCommented:
who setup your network originally, and did you record the changes made to the config of the DSL modem, and/or the server?

Since your one computer is having issues connected directly to the DSL modem, then likely there's is something wrong with the modem.

I'd get a new DSL modem if the other is several years old, and make sure that the new DSL modem will let just the one computer work that this no longer happens:

internet connectivity starts to lag and eventually stops working

Do you have a record of your original network config that you can put into the replacement DSL modem?
manch03Author Commented:
I select Test Router  from the menu on the router and it fails on the gateway and the dns...  That is what is making me crazy.  I can ping the gateway from the server and/or a workstation inside of the network.
manch03Author Commented:
I do not have the original configuration of the original modem as this is the 3rd modem to start doing this within 6 months.  I am getting a new modem, hopefully tomorrow and I will try swapping that out and see how it goes.
Rob HutchinsonTech Lead, Desktop SupportCommented:
Looking at the info given at this point:

I'd question if any configuration changes( made up to this point) actually were even needed as the network had been working fine until recently.

In addition to this, I'd wonder if you have a record of the original Netopia config, possibly a backup of the Netopia original config of when the network was working fine.

Since your network was working fine before and only recently started misbehaving, I'd suspect hardware first. Especially since you said that the router was several years old.

What you can do when you get a replacement router is use your old routers config onto the new router then see if the problems go away.
Rob HutchinsonTech Lead, Desktop SupportCommented:
what is the IP address

This doesn't look right.

from this:
screen shot
manch03Author Commented:
I saw that too and I do not know what that is...  I should call att and ask them what that is.
Rob HutchinsonTech Lead, Desktop SupportCommented:
yep, doesn't look like the right number to me.
manch03Author Commented:
It turned out to be the modem. After installing the new modem/router everything is working fine.
manch03Author Commented:
It turned out to be a bad modem.  Received the new modem and everything has been working well.  Thank you for all the help.
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