When you set up the VPN connection for SBS 2008 there is one thing to keep in mind if you use it a great deal in your business… out of the box it only allows 5 vpn connections
So you run the wizard from the networking section…
And that pretty much does everything you need to set up the VPN — you can read more about the nuts and bolts of what the wizard is doing from here:
SBS 2008 series : VPN setup in Small Business Server 2008 « Wintivity ™:
Once the wizard is finish it is … BY DEFAULT set up for only 5 vpn connections at a time….
To increase this value, click on start, go into the administrative tasks and find the Routing and Remote access section
Inside the RRAS find the Ports section, find the WAN Miniport (PPTP) and right mouse click on properties.
Adjust the maximum ports to whatever amount you feel is needed.