When one account is used for logins from several places at the same time, you need to shorten the Timeout duration of session of the user. For example, the default value can be adopted. Otherwise, if a user cannot log out due to timeout and thus occupies a large number of online user resources, other users cannot log in normally.
Cause one: This is a normal situation. The number of online users reaches the upper limit.
Cause two: The set session timeout time is too long when one account is allowed to be used for logins from several places at the same time.