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Users of our accounting server have a couple of times gotten odd errors about communication and unable to access SQL resources. When it happens it happens to all of our users at once. My first thought was maybe the SQL Server is out of whack but event logs for it look fine and no issues with the maintenance tasks that are scheduled.

The server does appear to be seeing an IP address conflict however at intermittent times that seem fairly close to the incidents. The MAC address is one of our laptops. All of our equipment excepting the usual stuff is DHCP, double checked and the server address is on the exception list so it should not be handing out at all. I've seen it where our VPN users had trouble because their LAN was on the same range as our LAN and their router wouldn't let them access our network because it thought everything was local but never the other way around. Has anybody ever seen this behavior where a remote LAN gave interference with the Local LAN?

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"our VPN users had trouble because their LAN was on the same range as our LAN" - WTF? No wonder you've got problems. Yes, its just possible to build a working network like this - but a really stupid idea. Even if that's not the cause of this problem, you need to sort it out. – symcbean Dec 20 '10 at 16:42
Our internal network is on, a lot of home network devices sit on like netgear and Linksys routers. When they try to go to a server sitting on say it tries its own local area connection since it is on its own range. This is not the issue here and I think your missing my question. – Shial Dec 20 '10 at 17:25

We have had problems previously with a VPN, where if a remote users IP range was set to the same as ours (192.168.0.x) then it would try and route traffic over their local router, rather than using the vpn. Soon as they changed this to a different range, then all traffic went over the vpn correctly.

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I've had that too, what I'm seeing here seems like somehow our internal network seemed to somehow see a remote users ip range and tried to route to it leading to a reported IP conflict (At least this is the only explanation I can come up with) – Shial Dec 20 '10 at 17:28

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