VPN Connection Causes Internal LAN Connection Loss with Server

Posted by sleepisfortheweak on Server Fault See other posts from Server Fault or by sleepisfortheweak
Published on 2013-11-08T02:39:53Z Indexed on 2013/11/08 3:57 UTC
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I've tried configuring basic PPTP VPN at my small business using a number of different tutorials. As far as I can tell, the actual VPN connection worked fine, but upon connecting a client, the Server 'disappears' from the internal LAN. The RRAS service must be stopped before the connection is restored.

My Setup:
The network is simply a DSL Gateway/Router to the outside functioning as NAT/Firewall/DHCP. The server is a Win Server 2008 machine at fixed IP 192.168.1.200. The server has 1 NIC, so I used the 'custom' option when configuring RRAS. The RRAS settings should be default except that I've disabled ports for connection types I'm not using and reduced PPTP ports to 10. I've also created an address pool and disabled DHCP packet forwarding.

The server only functions as a File Share and now a VPN Server. Local LAN computers all have mapped network shares to the server authenticated based on Local User/Group setup on the server.

The Problem:
The moment a client connects through VPN, the server 'disappears' from the local network. All mapped drives disconnect and there is no response to a ping 192.168.1.200. Even if the client disconnects, the server does not re-appear at that address until the RRAS service is stopped.

I've Tried:

  • Using an Address Pool inside and outside the local subnet.
  • Using DCHP Relay
  • Checking Inbound/Outbound filters (none enabled)

The fact that nothing I've tried has had any effect, and that I can connect and successfully obtain an IP tells me that it's something more fundamental I'm missing.

My gut tells me that it's something to do with the second IP address added by the VPN client somehow taking over the interface or traffic from the local LAN accidently getting routed to the VPN client instead of handled at the server once RRAS has become 'active' when a client connects.

Hopefully this may be obvious to someone with real IT experience. I've been doing this a while and almost never been stumped. I'm starting to think it might actually be something tricky since my setup is pretty basic yet refuses to work. I'll be happy to include more info if this doesn't ring any bells right away for anyone.

Thanks

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