All presence lights and icons go gray?

The client has lost connectivity with the internet.  If you have the client enabled to auto-reconnect, standby, the client will reconnect as soon as connectivity is restored.  You can also confirm the loss of connectivity by firing up the web browser on the Android/iOS device and attempt to navigate to your favorite web site (i.e., foxnews.com, cnn.com, etc).  If the browser fails to connect, it means your tablet/smartphone has indeed lost internet connectivity.  Please contact your network administrator.