A Defender Desktop Login user is able to login successfully at some times, however at other times it is found that the login fails. The user may see "Access Denied - no valid route found."
Examples from the Defender Security Server logs (when the Defender Desktop Login workstation is online):
In this particular example, note the User-Name value in the logs has a trailing space, showing immediately following the username and before the comma:
"User-Name: test_user , Request ID: 1"
Defender Desktop Login is passing the user-name value including the trailing space and this user does not exist.