Here's an odd one for you experts:
Skype for business runs happily all day, except between 11pm and 1:30am (approximately). If you have your info saved and cached it still signs on fine. However, if you click "delete sign-on information" at the login screen, or if you are running
a citrix client that clears it for you, you can't log in between those times. Sometime shortly after 1:30am you can log back on without any kind of issue at all as if nothing was wrong. The environment is a hybrid Lync 2013 and Skype for Business on premise
setup. These users are homed on the Skype for Business side of things.