I bought a new iPhone 11 and restored the backup from my iPhone 6.
It's great except for this issue; I can't get a longer auto-lock than 5 minutes.
I spoke to an Apple support rep and we worked out it's something to do with the exchange accounts I have set up on it.
I have one Office360 exchange account and 6 AWS exchange accounts, all used for email only.
If I disable the AWS exchange accounts, for some reason I get the "Never" option back. The Office360 account doesn't affect anything.
However we weren't able to work out much beyond this.
Why could this be?
Best Answer
I logged into my AWS WorkMail dashboard and noticed that there is a "Mobile policies" menu item.
When I chose this, one of the policy options was "Enable screen lock" with a value of 300 seconds - or 5 minutes, co-incidentally the maximum value in the iPhone's Auto-Lock drop-down.
After I disabled this and cycled the exchange accounts on the iPhone, the "Never" option re-appeared.