Freezing Slideshow

recently started testing 4 Xibo clients in our office.
a couple of them seem to freeze occasionally… after a day or 2.

Nexus players (OS 6.0.1)
**yes we have the newest Xibo to take care of the MAC address issue
there all on wifi.
they are all on the same network.
we had to use a 3rd party app to connect to our corp with due to credentials being neccesary (not just a wifi pw) Radius

2 of the devices have never frozen… 2 have…

any idea whats going on? and can you make suggestions?

i have enabled auditing and debugging but it has not frozen again since…