Hi Parth,
Please offer more information about your current environment, such as did you cluster your DirectAccess server, what client (Windows7 or what) you are using when you meet
this error, if you are using the following listed server please confirm you have install the corresponding update or hotfix.
You intermittently cannot connect to the DirectAccess server by using the IP-HTTPS adapter in Windows 8.1 and Windows Server 2012 R2
https://support.microsoft.com/kb/2966087/en-us?wa=wsignin1.0
Windows 8.1 or Windows 7 cannot connect over DirectAccess to a Remote Desktop Session Host server farm
http://support.microsoft.com/kb/2964833/en-us
You can't disable the NRPT in Windows 8 or Windows 8.1
http://support.microsoft.com/kb/2953212
"HTTP 403" or "0x80040001" error when a DirectAccess server requires OTP authentication in Windows RT 8.1 or Windows 8.1
http://support.microsoft.com/kb/2973071/en-us
I’m glad to be of help to you!
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