Skype for Business (O365) "Exchange needs your credentials." every day at 4:30 PM EST

I have been getting these requests for re-authentication for about a week now.  Never paid any attention to the time the window pops up.  I am usually too busy and just need to make sure I do not get signed out.  I'll try to make a note if it happens at the same time every day.

BTW, I also have problems getting my VVX 310 to sign in each morning.  It takes the credentials and then within a few minutes gives me an error saying there was some sort of Exchange problem and I need to sign out on the phone and back in.  The phone stays signed in the rest of the day.