Intermittent internet over the network

I have either no internet service or very slow internet over most of our network.  Everything was working well until recently.  We have a fractured T1 line with a Netopia r5300 router.  We have 2 Win2000 Servers (One is data/One is a Citrix Server) and a WinNT4.0 (Exchange & Domain).  T1 provider has done tests that show the problem is probably not theirs.  On the Citrix server the internet is up most of the time.  The other servers and all workstations (about 40) have the internet occasionally, however, it works for a moment and then nothing.  Even when it is working it is much slower that usual.  You can ping the gateway from anywhere, but if you try to ping a website, sometimes yes, sometimes no (once again from everywhere but the Citrix server).  Everything runs through two SMC 24 port switches.  I have switched the router to different ports on each switch with no luck.  There seems to be no other network traffic issues.  Also, I have scanned for viruses and there was a couple on 2 workstations but they have been removed.  
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Craig RoberdsMISAsked:
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mrpez1Connect With a Mentor Commented:
Often times T1 problems are intermittant. We had an issue where a repeater in the central office went bad and we'd have frame loss maybe 2 hours out of the day. Everytime they did an automated test, everything was fine (of course). When the actually came out and did a "head to head" test they found the frame loss.

If you hooked a computer directly into the router while you were having the problem and it went away, I'd look to a bad switch or bad cabling. If not, then you are back to the router and t1. You didn't say whether the router was CPE or not.

It's interesting that you can ping the router but not the internet. That would point to the router or T1 rather than an internal network issue.

Start with the switchs, you can get a new one for ~$100. I've had several die on me recently (especially linksys).

Also you might invest in a CAT-5 wiring tester...

Try hooking a computer up directly to the CSU/DSU to the T1. Take everything out of the equation but the T1, the netopia and your computer. That way if you still have the problem, you've eliminated your network as the cause. Is the netopia CPE? E.g. did the ISP provide the router/termination equipment for the T1 or did you? If it's yours the next step after eliminating the network would be to switch out the router and see what happens.\

When we have T1 problems they always tell me my router is broken. Out of 4 instances, they've been wrong 100% of the time.
Craig RoberdsMISAuthor Commented:
I hooked up the router directly to a computer and it works fine.  I put it on another switch with the same computer also no problem.  Once again, even the servers(which I uplinked with it's switch) had a good internet connection.  All of the workstations are connected to the same switch (no hubs, just wall connections) but have no internet.  I am thinking there may be some wiring problems, but the rest of the network has no problems.  I just recently inherited this network, so any suggestions would be appreciated.  The internet does work about half of the time, when one is down, everyone is down.
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Craig RoberdsMISAuthor Commented:
One of my servers went down last night (the Win2000 data server, which was the server that could not get internet) and I had to use the ERD, and amazingly enough, everyone has internet connection now.  I am looking at the events to see if I can see what happened.  If the internet stays up all day I'll close and accept your answer.  Thanks for all your help.  If it matters the error on the Win2000 was Windows NT could not start, Ntoskrnl.exe is missing or corrupt.  
Interesting. If indeed that server was the problem, it may have been flooding the network... I had a firewall that did that occasionally. It was very obvious as the switch lit up like a christmas tree when it happened. I would think that your pings to the router would have been either slow or you would have lost packets if that were the case.

Is it a Sql server? could have been the slammer worm...That would have definately have screwed with your available bandwidth.
Craig RoberdsMISAuthor Commented:
Yes it is a SQL with S2000 (Btrieve).  I am trying to see if it was a worm or a conflict.  After Windows updated on Tues morning that is when I began having errors and warnings in the log.  I knew there was a problem with the server, but I had been having internet problems since Friday so I did not think they were related.  After hours yesterday I rebooted the server and had the Ntoskrnl error, fixed the error with ERD, and now everything is working, I just need to find out why.
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