Q: latest update for iphone6plus

Trying to install the latest iOS 9.3.1 onto iPhone6 Plus.  Cannot turn phone on as the screen just has a logo of lead to iTunes on it.  Have connected to iTunes on laptop.  But after 50 mins of trying to download it a messages comes up that it is unable to do so and iPhone must be restored.  Hit restore button and a box comes up saying error 1671.  Have gone through all the suggestions such as checking lap top has latest updates and have turned it off and back on again.  This also happened for the iOS 9.3 but eventually it got installed after trying several times. 

Tried calling Apple support several times but they are very busy and the wait time is very long and then you get cut off.

Any  suggestions as to what to do?