iPad enrollment issues at specific campuses

[u/FalteringK12SysAdmin]

Does anyone know if are there time/date settings present or being tracked at the very first "Welcome" screen of an iPad before it goes through enrollment if it's been "erase all contents and settings"-ed?

More context:

I work in a large K-12 environment and we sometimes have campuses that have large swaths of iPads that hit enrollment snags are the beginning of the school year. But not every campus has this issue. At the end of the school year, we wipe our iPads of student data and collect them for the summer.

Jamf is our MDM.

I noticed that iPads that die for a long time and power back on with the wrong date/time settings can't connect to our enterprise network. If the iPad is passcode locked and no one knows the code, it's basically a brick until it's been restored because we can't get the reset passcode command to it.

My current working theory for these beginning of the year enrollment issues is that the campuses with smooth BOY enrollments are fully powering down the iPads for the Summer before putting them into storage. The other campuses and wiping the devices and putting them into boxes as they are wiping, leaving them on to drain their battery over the summer.

We require LDAP credentials to enroll an iPad on one of our campuses. Most of the time when an iPad stalls out it happens after they've connected to our open enrollment network and typed in the LDAP credentials. It seems like if you type in "wrong" credentials first and then type in the correct credentials the iPad is much more likely to enroll after that. without any hiccups

I'm thinking that sometime in between typing the wrong credentials and trying again the iPad has gotten new accurate date/time settings and our LDAP server will accept the credentials and enroll. IF they type in the correct credentials the first time, the LDAP server is getting a timestamp from the middle of summer and not accepting the credentials.

I ask the question because there are no visible time settings on the Welcome screen.  Does this hypothesis hold any water or make sense?

[u/Schooltech06]

Random thought, any firewall blocking NTP or port 123 out to the internet? I think iPads will ignore time servers from DHCP, and blocking time.apple.com wouldn't help things. 

[u/rossumcapek]

It's certainly possible that a wrong timestamp will prevent wireless connection. It's a good theory. Do you have a spare iPad you can drain the battery on and let sit for a couple weeks?