Hello Neverthrive,
I saw your crash reports via Google last week on M and Tuesday on N. Thank you for reporting them - it's the only indication I get that something has gone wrong in the field.
Unfortunately there's no way to reply via Google so I couldn't reach you. But I did check it out and there was a programming error where a null entry for the "iperf test duration" setting would crash the program.
I made a fix (along with a number of pending changes) and posted v16 on the Google Play Store yesterday. Please try upgrading to v16. Either way, whether it works or not, please drop me a report on ctodeveloper.arubanetworks@gmail.com.
Thanks so much for reporting this bug,
Peter T