I showed the app to a coworker of mine and he promptly crashed it.  There were some issues with lingering unresolved network addresses when the start and stop buttons were repeatedly pressed in rapid succession.

So that has been fixed and I’ve also added the ability remember the last 4 IP addresses used.

Play store link: https://play.google.com/store/apps/details?id=com.kaytat.simpleprotocolplayer