I've stumped most IT professionals I know with the latest VPN connection nightmare I'm experiencing.
Configuration is as follows:
1. SBS 2011 Standard running on local net starting with 192.168.XX.YY where XX is a number other than the default 1.
2. Basic small business setup with <15 users, remote access, exchange, etc.
3. Static IP address from router used for all local clients and access to remote.server.com access via RWA.
4. Port 1723 & GRE Protocol 47 is active on the router along with the basic necessary ports.
5. Windows Firewalls rules on both the client and server set to allow TCP 1723 & GRE traffic incoming and outgoing.
6. Server is handling DHCP (disabled on router).
Experiments with results:
a. Internal VPN connection via Windows client using server IP address of 192.168.XX.Y works successfully and clients receive internal IP from the local net of 192.168.XX scope.
b. VPN connects successfully externally to public IP with PPTP with any user credentials on Mac (10.6.X) or iPhone 4 and up.
c. VPN fails miserably with Windows 7 clients using PPTP with error 806. The event log registers event 20209 - indicating there's an issue with GRE (but reference previous experiments and setup point 4 & 5 above). I tried connecting with the Client and Server firewall disabled and it didn't failed again.
I initially blamed the router & GRE 47; ISP installed the router to go with fibre connection (and cannot be changed), but according to the event log when the VPN is successful via phone or Mac it displays the GRE message, but we never see the GRE traffic message when the connection stalls on Windows clients.
I don't claim expertise in SBS management and would appreciate the help. Any ideas or experiments are greatly appreciated. This has been driving me nuts for almost a week!