Error 631
Solutions:
1. Win+R, input and run regedit.2. Find the follow key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL
Add a new "D_WORD(32bit)" with mouse right click, change name to SendExtraRecord
3. Double click SendExtraRecord, and change the value to 2, save and close Register editor.4. Reboot, and try SSTP again.