constant re-registration

For the past few months, xfinity has required me to re-register my modem every two weeks.  This is a new phenomena.  It is very annoying as it always happens early in the morning when I am trying to read the news and check my email.  The really annoying thing is that once I follow the procedure xfinity requires to register, It takes 10 minutes for the registraion to take effect.  I don't understand why it takes so long.  In this age of fast connections and almost instant logins, having to wait 10 minutes is completely unsatisfactory.  Can someone please explain why I am constantly being un-registered?  As I mentioned, this problem is recent.  I have been an xfinity subscriber for many years without this problem