Users in Apple’s forum reported some common problems that are listed below...

• Battery health drops after upgrading to the latest iOS.
• App store crashes after upgrading.
• iPhone freezes and doesn’t turn on.
• Stuck on Activation screen/ stuck on loading or apple logo.
• iPhone stuck on “Hello” screen
• iPhone 6s frequently restarts
• Error 69 on iPhone update.
• Stuck on Boot/ Boot-loop issues on iPhone 6s Plus

Some users have reported other problems with similar symptoms on their phones which loosely qualify under the iPhone 6s Plus software issues. Some user thinks that the no signal/ no Wi-Fi problem falls under the “software issues” category, but it is a separate issue which requires a separate mode of service.