Error Description:

Possible Cause: This issue may occur if no SSTP ports are available on the server.

Possible Solution: To troubleshoot this issue, verify that the RAS server has sufficient ports configured for remote access. To do this, follow these steps:

Start the Routing and Remote Access MMC snap-in.
Expand the server, right-click Ports, and then click Properties.
In the Name list, click WAN Miniport (SSTP), and then click Configure.
Modify the number that appears in the Maximum ports list, as appropriate for your requirements, and then click OK.
Note By default, 128 ports are available for this device.
In the Port Properties dialog box, click OK