We recently purchased 2 iPads (Pro 9.7 inch). Both are are running ios 10.3 We are having daily issues with both devices connecting to the Wifi network in the office. The wifi password is 10 characters (numerals, lower case characters, no special characters). I enter the password (correctly) between 3 and 12 times before it accepts the password. It then will stay connected until the device sleeps, then it loses the network connection and will not remember the password. We also have two iPhones running ios 10.3.2 that cannot connect to the wifi network at all (entering the password no matter how many times and it just keeps asking).
I know I'm entering the correct password as I created a file where I typed in and triple checked the password, then copied to the clipboard and pasted. No extra spaces or characters are included.
I know it's not the wifi network - both my iPad 2 (running ios 9) and my Mackbook Pro connect first time everytime. No problems remembering the network or the password. It's only these 4 devices with ios10+ that 1. can't connect to the network without entering the password so many times and sometimes just waiting for some undefined amount of time to pass and 2. won't remember the network name or password.
I tried setting up using the Other option - it allowed me to connect after several tries but it doesn't remember the network the next day (or even after it goes to sleep for awhile).
The Applecare first level person I talked to thought it was a hardware problem. But that seems ridiculous when I have two iPad Pro 9.7 inch and two iPhones, all running ios 10 that are having the exact same results. I tried resetting network settings but not resetting the whole device yet - I will test on my personal wifi network first to see if it remembers that network after a few days of not connecting.
Overall, Apple is pretty disappointing. They seem to have taken lessons from Microsoft on how to mess up a perfectly serviceable operating system. Worse, they don't want to acknowledge that it is a problem in their operating system or provide a way to resolve the problem.