Did you do anything special to avoid the camera restarting when custom.sh kills and restarts ppsapp?
I’ve got most things working, but in order to get the logs, which would trigger MQTT the camera simply reboots in 90% of the cases.
When it doesn’t reboot, the RSTP port in not listening anymore, so no picture. 
Looks like the issue stemmed from killing and restarting the ppsapp in quick succession. During the startup of the new app the resources used by the killed one (open sockets, etc) were not cleaned up fast enough, hence the lack of RTSP.
Adding a sleep 5 between the kill and restart resolved the issue.
Doubt question here 
What is ppsapp ? I was trying to Google but really without success