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)