I am using a Fritz!Box router which also is the interface to the DSL Internet connection. Whenever the DSL connection is forced to reconnect (IP Change) the video running on Z9S is stopped. I have to reboot the Z9S, because the network is no longer available. This does not occur with a Rasperry Pi + Kodi in the same enviroment.
sorry english but i'm using translator. I have the same problem you have with fritzbox7590 and z9s try to put fixed ip on z9s no in dhcp.