I took on a client today that has Microsoft VPN tunnels between two offices several miles apart. They claim the VPN worked until a few weeks ago.
Their gateway is a D-Link Wireless Router Model DIR-615. It has PPTP configured as a Virtual Server to pass through to the Server's IP address over port 1723, and under Application Level Gateway both PPTP and IPsec are checked.
I have restarted Routing and Remote Access, Restarted IIS, and even installed all the Windows updates and restarted the server itself.
From an internal client, I can connect to the VPN without issues. Once I move to the WAN, I get the 800 error if I connect with the client Security Type of VPN set to Auto. When I force it to use PPTP, I get error 807.
Using canyouseeme.org from the server, it says port 1723 is open.
I created my own admin account and used those credentials to make sure it wasn't an authentication issue, and still can't connect.
What am I missing here?