I have a Sony Xperia Z5 Compact running Android 7. The Wifi hotspot/tethering functionality has never been perfectly stable, but in recent weeks/months (I think since Android 7) it has become awful. What happens is I unlock the photo, pull down the notification screen and tap the hotspot icon to turn it on. The hotspot icon then shows in the top notification for about 2-3 seconds before vanishing again (I presume: crashing silently). If I turn it on again sometimes it also vanishes within a few seconds, but it may then stay on for a while. However, it stops relatively frequently (several times an hour).
It does not appear related to what devices are attached (it crashes before any other device has connected, after all) nor to the mobile data connection (which is usually working fine with good signal at the point it crashes). My provider does allow tethering, and anyway it's the hotspot wifi functionality on the phone itself which is cutting out and dropping the wifi to the tethered laptop, not the onward connection.
Obviously I'd love to know the solution directly, but even if not: is there any way I can debug what's happening by viewing system logs or similar? Phone is not rooted and I'd prefer not to root it.