Are you referring to a disconnection message in the LightBlue Explorer app or in your Android application? According to the docs for the Android BLE API, "status =19" does indicate a disconnection from a peripheral, but there are many possible causes for this. Connection timeout is one possibility. iOS in particular is known to initiate disconnections after a certain period of inactivity, though it is not well documented exactly when or why this occurs (some say ~30 seconds, but others report it happening sooner, and it's hard to know for sure whether iOS itself is the culprit). Try setting the properties of one of the virtual characteristics to include "Notify" and subscribe to notifications from that characteristic from the Android app, and see if the connectivity issues improve.