I brought this 2.5 year old iPhone 6+ to a local Apple authorized lab/workshop & tell
them I have this issue: they ran a diagnostics & said it's not a hardware issue & should
be an IOS issue.
My wife had since upgraded the IOS from 9.x to 10.x & I recently upgraded it to 11.2.1
& still having this intermittent issue. The lab said if upgrading IOS did not help, may
need to wipe IOS out completely & reinstall : anyone thinks this will work?
I have quite a bit of photos, contacts & applications esp (MobileIron, licensed Mobile
threat Prevention tool) so reinstall is quite a hassle to me.
I can attach a screen shot of the diagnostics results if this helps