During hosting my login page get logout automatically why?

............ Now when I performed 2nd action identity null in asp. Net mvc it is getting logout automatically

1) First check where and all you have, redirection into login page.

2) One of those code is executing when you clicks the login buttuon.

This is may be happening because of the session has expired ?

https://it.toolbox.com/question/unexpected-logout-in-my-web-application-based-on-aspnet-c-and-sql-server-2005-050311

https://support.microsoft.com/en-us/help/315584/how-to-automatically-log-a-user-off-from-a-web-application

https://www.phpbb.com/community/viewtopic.php?f=46&t=950465

is there any timeout specified in your web.config file?

check for something like following:

here timeout="15" specifies timeout user login after 15 minutes

what is that value on your config?