Accessing Windows 7 VPN Server When DHCP Fails (PPTP)

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The Short Version: If your VPN client fails to obtain an IP address via DHPC when connecting to a Windows 7 VPN server using PPTP, it may be possible to connect to the server over RDP by accessing it at 169.254.128.230 if your client is assigned an IP in the same network range.

Last night I was logged into my Windows 7 desktop system back home, which runs my home automation software and acts as a VPN server. I recently had to setup the VPN server again and was trying to troubleshoot the problem of VPN clients not receiving DNS server addresses from the server.

At one point I changed the server configuration from providing a specific range of IP addresses to instead provide IPs via DHCP. After making this change I could still connect to the VPN but my client received a 169.254.128.x address and I could no longer access the server over RDP at the previous address.

I was accustomed to thinking of the 169.254.x.x range as being a sign of a problem and not as a useable network range so I kept trying to access the original, internal network via various methods (trying to override my VPN client assigned IP, using a virtual machine with a shared network connection but on the original network). I even tried to RDP to 169.254.128.1 but it also failed.

Finally, at some point I realized that there was an entry for a default gateway in my VPN client settings. In my case it was pointing to 169.254.128.230. I’m not sure if this is always the case.

When I entered this address into the RDP client I was able to connect and then set the server back to distributing the specific range of IP addresses that were previously defined, instead of using DHCP.

I haven’t resolved the original problem but I was able to get back into the machine and restore the VPN setting.

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