Avi-on is a secure system, and that means that we work hard to prevent others from accessing our software and your network.
One way to maintain security is to make logins expire after a fixed period of time. If you like to use the "set it and forget it" feature, then you were probably reaching for the app after a week or more. As a result, your login probably expired and you need to re-enter your username and password.
We are reviewing whether we can make the login expiration a longer period of time. Please let us know if this is something that is important to you.