Timing the death of wifi

You can find a bunch of related apps by searching for "wifi analyzer" in google play. Searching for "wifi analyzer export" only yields a few results, including Wolf Wifi Pro Net Tools Demo, which apparently has some export functionality.

Perhaps you can use Tasker to run this and export the results every 10 minutes or so.

 

Yes, it's very easy if one is comfortable using Linux, the embedded operating system of the Android phone. If "BusyBox Pro" is installed then one has all the usual commands at ones disposal, so it's just a matter of creating an executable script, and using an app to run it every so often during the suspect timeframe. A Play Store search for "crontab" yields several candidates, but the suggested "Tasker" may do the job.

In this simple example, we're just going to "ping" an outside machine to see if the wifi interface is working. If it isn't working then we write the time to a file, along with any other information you'd like to see at that time, perhaps the top several apps consuming the cpu (commented out below as it's not really necessary for your stated purpose). If you ran this script every minute from 10:00 pm to 06:00 am then the first line in the file would be the first minute that the wifi interface (wlan0) failed, with remaining lines indicating continued failure or the lack of them as intermittent success.

ping -c1 -I wlan0 google.com >/dev/null 2>&1
if [ "$?" -ne "0" ]; then
echo $(date) "wifi is DOWN" >> /storage/emulated/0/wifi_results.txt
#top -n1 >> /storage/emulated/0/wifi_results.txt
fi