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System Error 53 Network Connection Could Not Be Found

Hi Guys,

We've got a client that has Demon Internet ADSL broadband into a Cisco 870 which is then fed into a Cisco Small Business switch to which the Windows Server 2003 server and all the office PC's are connected.
Every so often (about once every 2 months) the network goes down. This includes internet access and access to the server.
We cannot ping any machine from any other machine and when we even just power on the server and a single PC and try to ping the server we get 'System Error 53, Network Connection Could Not Be found'
We have tried to connect onto the WAN side of the router to confirm it's an internal error but this keeps dropping out (i.e if we ping -t) this drops every 5 or 6 PINGS although Demon have stated that the line is stable.
We then went around and tested all the PC's again and this time we got PING replies that also kept dropping and got between 50% and 75% packet loss.
This occurs every couple of months and then without reason goes away and the all works fine.
The fact that we could not ping machine to machine (with static IP's) and that we have replaced the router and switch leaves us without an answer as to what the problem is.
We are currently looking to replace the server NIC card and then possible get the building wiring checked but is this the correct 'logical' next step ?
(Apologies if this is in the wrong Zone)
Thanks
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Netexperts
Asked:
Netexperts
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3 Solutions
 
NetexpertsAuthor Commented:
As an addition:
We've just set 2 PC's to the following IP's
192.168.0.15 and 192.168.0.100
Tried to ping 192.168.0.100 from the other and got:
Destination Host Unreachable
Reply from 192.168.0.15...........
Reply from 192.168.0.15...........
Reply from 192.168.0.15...........
Reply from 192.168.0.15...........

And then tried to ping the server (which is on 192.168.0.1) and got :
'Transit Failure'

Then checked IPCONFIG on the 192.168.0.100 PC after setting the NIC to pick up DHCP and DNS dynamically and these picked up an APIPA address.

Not sure if this helps.
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BudDurlandCommented:
It sounds like the Cisco small business switch has failed, or is in the process of failing.  I would first try swapping that out.
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Netman66Commented:
A few things come to mind here.

1)  Your subnet mask might be incorrect on the internal interface of the server or switch/router and not in the same segment as the addressing being given (or set) on the client.

2)  Your DHCP scope did NOT exclude the addresses of the switches, router or server.

3)  Your DHCP server handed out the x.x.x.0 or the broadcast address because the scope was setup incorrectly.

If you've already swapped the switch and router then I can't believe it would still be those causing the issue.

You also want to make sure your clients and the server itself DO NOT use any other DNS server but your own.  No ISP DNS server addresses are to be on any NIC inside your LAN.  Setup Forwarding on your DNS server or rely on Root Hints only.

Let us know.
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NetexpertsAuthor Commented:
Sorry, yes we have replaced both the switch and the router.

Even if there is a misconfiguration on the DHCP or DNS then setting it statically on 2 PC's should allow them to communicate wouldn't they ? although they don't.
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Netman66Commented:
Make sure you enable portfast on the switch.

You may also want to post the switch config so we can see if there are any obvious issues.

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dosdet2Commented:
Here are some testing ideas.

Get a cable long enough to go between the two computers that you are testing on, (either a crossover cable or put an known good switch (not one currently being used) and see if it fixes the problem.  I'm suspecting you have a wiring problem (layer 1).  

You could also get a cable tester (This is the one I use -> http://www.bestlinknetware.com/product-detail.asp?sku=260103 ) and test the cables, including any cabling built into the building, between the two computers.  

Be aware of the traffic on the rest of the network when the problem happens.  There could be a broadcast storm from one of the workstations that is killing your throughput.  When the problem exists, unplug all the workstations from the switch except the two test workstations.  Does the problem go away?  If it does, keep your ping running and plug in each workstation - one at a time - and watch for the problem to begin again.

If you are using wireless for one of these test computers, change the channel on your wireless AP and see if that helps.  You may have a competing wireless router near or electrical interference.  

Are there large motors, or electrical boxes/lines around (for wireless), or does the cabling run next to power cabling in the building?

Let us know what happens.
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dosdet2Commented:
One note, if the direct cable between the server and the test workstation does not cure the problem, then I would try reloading the drivers for the NIC card first, then look at replacing the NIC card if that didn't work.
Also nake sure all NIC cards are set for Auto Negotiation (for speed & duplex).
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NetexpertsAuthor Commented:
We finally found the issue was with a switch someone had installed as there wasn't enough network points in the room and they'd connected one port to the next with the same cable and so appeared to cause a loop.
We did replace the Cisco switch which appeared to resolve the issue for a few days but then the problem came back. Since we removed the extra switch it's been fine.
Points split for time taken to help if that's ok.
Thanks
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