exclamation mark in network status

I have been using my tablet a lot lately for remote focus. Tonight the little exclamation mark in the bottom righting hand corner of the screen started to come on occasionally and now it's on all the time. I'm still connected and have control of my units. What are some reasons why it's on?
I'm on a Hog 3 as a server with Dp2000 (the network status is good on the Server) running 3.1.4
I have good WiFi reception.
Thanks in advance for any input