weird LAN issue

So I helped set up some computers in a business office. They are running a piece of software that requires all of the computers to have static IPs. When I originally set everything up, the whole system ran fine.

Just a couple days ago the host computer lost its internet connection (without any setting-change or updates). The computer shows as having a perfectly fine wired network connection, but yet it can't communicate with anything on the network.

I've searched through 20 pages of google and none of the solutions have helped yet. Do you guys have any idea?

Thanks,
Nick

Make sure that DHCP is turned off on the router. It sounds like something else plugged in and grabbed the IP that one had been using.

My first thought would be a firewall issue - no-one "helpfully" installed a new firewall to "protect" the host pc did they?

Can it view web pages? Also, can it ping webservers such as google or newegg? I had one awhile back that could ping anything but couldn't view web pages or share files on the network. Got it down to symatec but no one knew the admin password. Start it in safe mode and see if the problem is resolved. If it is then it is software.

Also you can try and ping the loopback 127.0.0.1 and check the hosts file.

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Originally Posted by x88x

Make sure that DHCP is turned off on the router. It sounds like something else plugged in and grabbed the IP that one had been using.

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DHCP was already off... :-/

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Originally Posted by slaveofconvention

My first thought would be a firewall issue - no-one "helpfully" installed a new firewall to "protect" the host pc did they?

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I checked and doubled checked for anything like that. I also did a system restore to 1 week previous (when it was working fine) and that didn't help. Also turning off the windows firewall doesn't help.

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Originally Posted by DrkSide

Can it view web pages? Also, can it ping webservers such as google or newegg? I had one awhile back that could ping anything but couldn't view web pages or share files on the network. Got it down to symatec but no one knew the admin password. Start it in safe mode and see if the problem is resolved. If it is then it is software.

Also you can try and ping the loopback 127.0.0.1 and check the hosts file.

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It can't load any web pages. I tried pinging a couple websites to no avail. I also tried safe mode + networking but ran into the same issue.

Other than simply pinging 127.0.0.1, is there anything else to check the hosts file? I tried that, and everything went through.

Thank you so much for all the help so far.

-Nick

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Originally Posted by Indybird

It can't load any web pages. I tried pinging a couple websites to no avail. I also tried safe mode + networking but ran into the same issue.

-Nick

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I assume it can't ping local machines either? Try uninstalling the NIC and reinstalling it. Or chuck a new one in and try that.

Make sure the netmask and gateway didn't get changed. From what you've said, I can't think of a good reason why they would have, but..you know. :P Can you ping anything on the local network? Are you getting any activity lights on the NIC and the router (for that port)? Try DrkSide's safe mode suggestion to rule out most software interference. To rule out all software problems, you could try booting to a Linux live-cd, set up the NIC with the required parameters, and see if you can get through to anything. Hmm, along the lines of my original thought, just to be sure, try pinging the IP that machine is supposed to have from another system..then try pinging that same IP with the first system turned off.

After a few attempts I noticed something. When I restart the computer, or disconnect and reconnect the LAN cable I get internet for a few seconds, but it goes away before I can load the first page.

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Originally Posted by mDust

I assume it can't ping local machines either? Try uninstalling the NIC and reinstalling it. Or chuck a new one in and try that.

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Tried reinstalling the NIC, that didn't help. These computers are mini-itx and their open slot is already taken up, so I cant try another NIC.

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Originally Posted by x88x

Make sure the netmask and gateway didn't get changed. From what you've said, I can't think of a good reason why they would have, but..you know. :P Can you ping anything on the local network? Are you getting any activity lights on the NIC and the router (for that port)? Try DrkSide's safe mode suggestion to rule out most software interference. To rule out all software problems, you could try booting to a Linux live-cd, set up the NIC with the required parameters, and see if you can get through to anything. Hmm, along the lines of my original thought, just to be sure, try pinging the IP that machine is supposed to have from another system..then try pinging that same IP with the first system turned off.

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There are activity lights on the NIC and the router, but I can't ping anything on the local network.

Thanks,
Nick

Check the cable for any loose connections or kinks. Also, have you tried rebooting the router? Sometimes when caches and buffers get full strange things happen.

Can you plug it into a different router? If the problem persists when connected to a different part of the network with a different cable, then that narrows it down to just that machine. If the NIC can sometimes but not always communicate with other machines and a faulty patch cable or router are ruled out, I'd think that the NIC is bad. Since it's integrated that's bad news.:(