This error message in the event logs:

	The Secure Socket Tunneling Protocol service either could not read the SHA256
	certificate hash from the registry or the data is invalid. To be valid, the
	SHA256 certificate hash must be of type REG_BINARY and 32 bytes in length.
	SSTP might not be able to retrieve the value from the registry due to some
	other system failure. The detailed error message is provided below. SSTP
	connections will not be accepted on this server. Correct the problem and try

	The system cannot find the file specified.

...can mean that a network adapter is not connected.